Spare to the Throne - TV Tropes

"My parents were... rather traditional. They wanted the heir and the spare, and I was left in the cold."

• Alec from The Bride of Adarshan, as an illegitimate prince born of a mistress, was brought to the palace for this reason when the proper prince (now king) fell extremely ill. He's internalized it so much that he sees himself as nothing but his brother's shadow. That said, he has no desire to be king, as he's not suited for it, despite some people worrying that he's going to usurp the throne. Tragically, his mentor and Parental Substitute falls under that category, and tries to kill him for it.
• Cesare - Il Creatore che ha distrutto features historical examples Cesare Borgia and Giovanni de'Medici, sons of two of the most powerful families in Italy, though not quite royalty. Both were set on the path that noble second sons were often forced into in real life — the church. The problem? Cesare's older half-brother, Pedro-Luis, was killed (the manga has it that Ferdinand and Isabella saw him as a threat to their power and did away with him). This leaves Cesare's younger brother Juan as heir to the family's secular power. Giovanni is the second son of Lorenzo "The Magnificent" de'Medici, a humble, common banker who is more-or-less dictator of Florence, who made a deal with the pope to have Giovanni made a cardinal as soon as he graduates from school.
• Chagum in Moribito: Guardian of the Spirit is the Emperor's second son, and Spare to the Throne. Unlike most examples he did apparently receive schooling because his older brother suffers from a Soap Opera Disease, and becomes the heir apparent after his brother succumbs to it halfway through the series. In either case, he is remarkably calm (although clearly not-too-pleased) about it.
• One Piece: As a flashback shows, Sabo's parents adopted Stelly, a noble child of even higher status than him, as Sabo kept running away to see Ace and Luffy, among other "lower-class trash" in their eyes. The parents expected Sabo and Stelly to get along, but since the latter was a dick like the other nobles, and only Sabo was kind, it didn't turn out too well. Sabo was shot by a World Noble and presumed dead, ended up with amnesia and was taken in by Dragon's Revolutionaries... while Stelly grew up to be the king of Goa Kingdom.
• In Red River (1995), Prince Kail Mursili has a number of older brothers and half-brothers who have claim to the throne before him. Just about everyone, those brothers included, agree that Kail is best-suited to rule, though. Nakia, meanwhile, is desperate for her own son Judah to take the throne. Given that her boy is the youngest of the princes, this means she has a lot of scheming to do to get the others out of the way, even when the poor boy has quite the Big Brother Worship towards Kail and does not want to rule. By the end of the series, all of Kail's older brothers are dead (including the one who succeeded their father, who appointed Kail as his successor since he didn't have kids) and Prince Judah permanently renounces his claim to the throne after also calling out his mother on her evil deeds. By that point, it wasn't a question of whether or not Kail expected to rule so much as when he would actually be taking the throne.
• The Rose of Versailles:
  • Louis Charles, Louis XVI's second male child, who finds himself the Dauphin of France when his older brother Louis Joseph dies. In a variant, both Joseph and Charles were still children when this happens (they were respectively seven and four), and it was diagnosed a few years early anyway. Louis Charles never gets to reign anyway, as The French Revolution abolishes the monarchy, but Marie-Antoinette proclaims him king Louis XVII the moment after his father's execution.
  • The king's brothers, the Counts of Provence and Artois, and the Duke of Normandy also hoped to invoke this trope in their favor. The Count of Provence then returns in the sequel Eikou no Napoleon-Eroica, calling himself King Louis XVIII after his nephew's death during prisony. While he considers himself as king of France since the moment of his nephew's death in 1795, he doesn't get to actually reign until Napoleon's defeat in 1814-and then is back on the run when Napoleon comes back, at least until his final defeat at Waterloo.
  • Also from the sequel we have Alexander I of Russia — who makes sure it doesn't happen: while his grandmother, Catherine the Great, planned to skip his father Paul and have him succeed her directly, she had a stroke and died just as she was about to put it in writing and make it official, and Alexander hid himself until Paul arrived, at which point he was the first to salute him as the new tsar.
• Kaguya-sama: Love Is War: In spite of belonging to the Shinomiya family, Kaguya is not particularly held at high regard by them, as they consider her a mere accessory to the family's wishes. This further implies that Kaguya is not among the siblings that would immediately inherit part of the empire (given that she has three much older brothers, one of whom has a young son), but would have to fulfill the conditions to do so. The truth of the matter is rather different. Kaguya is actually an illegitimate child, and thus isn't allowed to inherit the company (though her father does admit on his deathbed that he was planning on leaving her with full control of a smaller company).
• Inverted in the anime/manga version of The Heroic Legend of Arslan, where it's strongly implied that Arslan was to be the intended "heir" in this scenario as they were revealed to be a commoner adopted into the royal family and made the public heir so Andragoras could placate the citizens about the royal bloodline and have time to woo Tahamine over the years and father a real heir with them. However, Arslan started proving themselves to be a competent ruler and recruiting several powerful and talented allies and Tahamine never opened their heart to Andragoras. It wasn't long before Andragoras became antagonistic towards Arslan because they never intended this commoner to be anything more than a public distraction until they could replace Arslan with their true heir.

• Guardians of the Galaxy (2020): The origin of the Prince of Power. His brother was created to be the very epitome of the heroic ideal, actually born gleaming with heroic might. However, in the process the machine also created a spare, which immediately turned out to be astoundingly ordinary (their mother says an evil twin would've been something). So Prince Muscular becomes a great hero, and his brother Otherone becomes an office drone. Until he finds and, er, eats the Power Stone.

• Alicorn: Rainbow Dash is this despite being Celestia's only daughter. She may be Crown Princess, but her mother and aunt are both immortal, so she isn't expected to take the throne at any point. She didn't want the title in the first place, but it hurts a bit extra that it doesn't mean anything other than a bunch of formalities she hates.
• To Die at Dawn by Allronix, written for the King's Quest universe. Considering Alexander-Gwydion was a slave less than a fortnight earlier, while his sister was the one prepped for the duty, it's pretty justified.
• Loona Goetia: The children of Goetia royalty, like Octavia and Loona, are refered to as Precautionary Heirs, since their parents are immortal unless killed.
• A Man of Iron:
  • Antony Stark is very much low in the line of succession to Winterfell, being Ned's cousin and as such behind Ned's three sons, but Tywin still daydreams about having the more friendly - to him - Stark as Warden of the North.
  • After being legitimized, Jon Snow becomes this since he's even more closely related to Ned and Tywin thinks he would be even more biddable.
• White Knights and Dark Lords duology: Discussed in the second story, where Draco and Spike have a conversation about Draco's family situation and what options he has now; Draco expects he'll have to explain this trope, only for Spike (who reveals afterward that he grew up in an era when this trope was the norm in the non-magical world) to surprise him by summing the whole thing up as "And you're taking umbrage at going from heir of one Family to... not even being considered as a 'spare heir' for another."

• Frozen:
  • This comes into play in Frozen:
    • Hans mentions wistfully that he has twelve older brothers, and seems to have a bit of a complex about it. Since he'll never inherit his homeland, he wants to take over Arendelle instead.
    • There were plans to explore this in-depth with Anna, with her introductory song in an earlier draft being one called "More Than Just the Spare", but most of it was cut. The song had Anna lament feeling ignored and useless, hoping one day to find her own place in the community and be helpful. In the movie proper, she still makes comments suggesting she sees Elsa as superior, such as when she earnestly reassures Hans not to worry too much about accidentally hitting her, the Princess of Arendelle, with his horse, because she's "not that princess" and it's not as big a deal to hit her as it would have been to hit her sister, "It's just me." This is exploited by Hans, who takes advantage of her low self-esteem to manipulate her into trusting him. When Elsa became queen, she gets bumped up to heir presumptive, and soon finds herself needing to deal with the chaos that ensues when Elsa flees Arendelle, while retaining the inferiority complex associated with this trope. Rather than try to keep the power for herself, she promptly sets off in a blizzard to find Elsa and offer her help.
  • This is explored more in the sequel, Frozen II. Like in the first movie, Anna spends most of the movie assuming the role of supporting her older sister, but when Elsa suffers a Disney Death, Anna finds herself in charge in the middle of an international crisis while grieving for the loss of the last of her family. She has to talk herself into finding her own direction independent of her sister during "The Next Right Thing," musing on how she'd always lived for her sister and asking "How to rise from the floor when it's not you I'm rising for?" Elsa comes back to life, but steps down as Queen of Arendelle and moves away, and Anna is crowned as her successor.

• The Reluctant Illegitimate Heir variation occurs in King Ralph, twice. First, when all known members of the royal family are electrocuted in a photography accident, Ralph is discovered to be the son of an illegitimate child of a royal uncle. He's lived his whole life in the US, so he's hesitant to leave that behind. At the end Ralph realizes that the man who had been prepping him to rule was also an heir to the throne who didn't feel worthy to take the position, and who also at one point specifically referred to how much trouble being king was.
• One of the central conflicts in The King's Speech is King George VI's ascension to the throne when his older brother abdicates. He felt totally unprepared, largely due to a pretty serious stammer. Of course, this is Based on a True Story (see the real life section below).
• The Lord of the Rings: The Return of the King: More precisely Spare to the Stewardship of Gondor; Ruling Stewards are de facto Kings after the royal line of Anárion had died out. Being the second son of Denethor, Faramir did not expect to inherit his father's title, but that's exactly what happened because his older brother Boromir had died, and Denethor committed suicide.
• Marvel Cinematic Universe:
  • Thor: Because Thor, the Allfather's eldest son, has been exiled to Midgard, Loki, as the second son, becomes the regent of Asgard after Odin becomes indisposed due to the Odinsleep. In the past, it's implied that Frigga once held the office of regent (Sif and the Warriors Three initially believe that they need to speak to the Queen about undoing Thor's banishment), but now that Loki has come of age, he inherits the position. This deleted scene makes it clearer:

    Frigga: Thor is banished. The line of succession falls to you. Until Odin awakens, Asgard is yours.

  • Black Panther: Wakanda Forever: Shuri is King T'Challa's much younger sister and never expected to rule, turning her attention to science and technology instead. However, when her brother dies of a sudden illness, and her regent mother follows barely a year later, she is unexpectedly thrust into the position of Queen.

• Andromeda: In "The Prince", Dylan and Tyr find themselves co-regents to Prince Erik of Ne'Holland, the only survivor of a Ruling Family Massacre. Notably, Erik is doubly the spare in that he was his father's third son, who was never expected to be king, and had never trained for it as his older brothers had. As a result, in addition to helping Erik reclaim his throne from the ruthless group of barons who had killed his family and put an end to the civil war on his planet, Dylan and Tyr must provide the young heir with a crash course in politics, Tyr's Nietzschean cynicism contrasting against Dylan's more idealistic approach. After Erik is crowned, he decides to make Ne'Holland a democracy.
• Bridgerton has a peerage version. As Anthony points out, he can afford to slack on wife-choosing and heir-siring because he has three brothers who can inherit the title of Viscount Bridgerton. Second son Benedict is feeling a little lost and turns to art, so he's a little taken aback when Anthony challenges Simon to a duel, because Anthony will either die or be forced to flee the country, meaning Benedict will have to step up to the plate.
• The Crown (2016): The historical example of George VI is very important to Season 1. George VI was George V's second son, and he had not expected to inherit the throne. The series does a good job of showing George VI's perspective on events: he had set himself up as an ordinary-if-unusually-comfortable naval officer with a happy marriage and two daughters living in an ordinary (for the neighbourhood)-if-unusually-comfortable townhome in Piccadilly. Then his brother decided marrying an American divorcée was more important than his duties and abdicated, leaving the newly-minted George VI with a crown he never wanted and wasn't entirely sure he could handle. Then he not only has to be King, he has to be King during World War II. No wonder the man smoked so much that he died of lung cancer at 56. His daughter, the newly-minted Elizabeth II, shares George's opinion, never really wanting to be Queen (or at least, wishing she could have raised her children before becoming Queen) and forces her uncle to realise that his abdication had hurt her, as well.
• Harry & Meghan: The real life of a spare, in an era when the monarchy is essentially a public relations enterprise, is explored, with Prince Harry and his wife Meghan telling their story and explaining why they moved to California to start a new life.
• Deus Salve O Rei: When Prince Afonso of Montemor goes missing after being attacked by bandits, his younger brother Rodolfo becomes the unexpected heir, a job that he really doesn't want because he prefers the life of a rich knob enjoying all privileges without any responsibilities of a king.
• Late in the first season of Galavant, it turns out that Richard was the geeky second son and that his parents wanted his older brother Kingsley to inherit the throne. But Kingsley didn't want to be "given" anything, or so he said, and left to terrorize the countryside for thirty years before coming back to take Richard's kingdoms from him.
• Game of Thrones:
  • After his brother's death at his own wedding reception, Tommen is next in the line of succession. His grandfather Tywin wastes no time in beginning his training. He's even betrothed to Joffrey's widow afterwards.
  • Viserys Targaryen was this in his childhood since Rhaegar was supposed to become king. Then came the Rebellion, Rhaegar and his son died, and Viserys thought to be the legitimate king. But as Rhaegar had the time to marry Lyanna Stark, that means Jon Snow is actually born legitimate and the ultimate irony of Viserys's life is that he has never been the true rightful king to begin with.
  • Another version of this happens when Heroic Bastard Jon Snow takes Winterfell back from the Boltons. Since as far as anyone knows, he is the last living son of Ned Stark, he is crowned King in the North. In actuality, Bran is still alive and Jon is actually Ned's nephew from his sister Lyanna Stark.
• House of the Dragon:
  • King Viserys Targaryen tells his daughter Rhaenyra he needs to have more kids. He reassures her that she is the heir, not to be replaced; he merely wants another kid as backup, because having only one heir is precarious — especially when his current backup heir is Daemon. Given that Rhaenyra actually dared Daemon to kill her in this very episode (even if she was confident he wouldn't), he arguably has an unassailable point. Though that decision to make more children ends up causing a Succession Crisis and Civil War in the end.

    Viserys: I could never replace your mother, no more than I intend to replace you as heir. But you are my only heir, and our line is vulnerable, too easily ended.

  • Aegon II was just a spare but the Hightower side of his family tried to train to him be heir despite he never being chosen by his father. He became King anyway because his mother said that his father did choose him. His enthusiasm for his role is not matched by his ability and he is expected to just be a figurehead.
  • Aegon's son Maelor is not be expected to do anything either since his elder brother Jaeherys is heir. This changes when the older boy is murdered.
  • One of the aforementioned children, Aemond, resents his older brother Aegon becoming king (though not of Aegon's own volition), for Aegon is ill-suited to be king while Aemond would be a better choice.
• A second modern example: Prince George from The Palace. For most of the series, he shows no interest in ever being a monarch, and tells his older sister Eleanor that if their brother Richard dies, she can be queen. However, when Richard's legitimacy is challenged in Episode 8, making George's ascension an imminent possibility, he starts to think that it might not be such a bad deal. (Of course, being an immature Royal Brat, he would almost certainly fail spectacularly in that role.)
• Though they aren't royalty, Jayden is essentially this to Lauren in Power Rangers Samurai. While she's in hiding, Jayden pretends to be the sole living heir to the title of Red Samurai Ranger, and with it the leadership responsibilities to the other Rangers. He doesn't really have an issue with being team leader as much as the fact that it's not rightfully his position. Lauren later demotes herself to spare when she realizes Jayden is better at leading the team than she was.

• Warhammer: Age of Sigmar: Runefathers, the Duardin who rules a Fyreslayer Lodge, typically have many sons specifically because of this trope; at least a few sons are guaranteed to die in battle, so having multiple heirs is smart. The title of Runefather doesn't pass to the oldest, though: it goes to whichever son he deems fit to lead. Sucession crises are common if the Runefather dies without naming an heir, and when he does, it's common for the other sons to leave and start their own lodge elsewhere.

• Cinderella (Lloyd Webber): Prince Sebastian's older brother Prince Charming is gone, meaning Sebastian was shoved into the position of heir.

  Sebastian: Now that I'm next in line
  I've had to grow up
  Cinderella: Now you're crown prince fancy pants
  Sebastian: I never saw that coming

• The Prince of Egypt: In "Footprints on the Sand" Moses muses about how lucky he is to be the king's second son since he can afford to goof around, but also knows that it means he won't amount to much historically.

• Encouraged in Crusader Kings 2: if your current character dies without an heir, it's game over, but the time period is extremely capricious and deadly. If you put all your hopes into one heir, and that heir dies before taking the throne, you're done. But if you have several heirs, then you're safe even if a couple of them bite it. Of course, this almost inevitably results in a succession crisis every time your current ruler dies, but them's the breaks.
  • There can be a number of problems with multiple sons though. Such as the various things one has to do to keep them all happy. And if you have gavelkind succession your titles are split up among your sons. While if you're a Muslim unlanded sons generate Decadence, and considering that Islamic rulers are expected to have multiple wives a lot of sons are expected. Such situations are practically guaranteed to produce a Succession Crisis.
• Dragalia Lost has the main protagonist, Euden, be the sparest heir in the Alberian royal family, being the seventh born child with his twin sister Zethia being the eighth.
• Dragon Age:
  • Dragon Age: Origins has this in Alistair, who reveals early on that he is of royal blood... unfortunately, he's a bastard, so he wasn't raised to the task. Needless to say, he's not happy about the idea of becoming king after being trained for something completely different and being quite forcefully assured that his illegitimate status would prevent the question. Word of God confirms that he is the illegitimate child introduced in the tie-in novel The Calling, which further reveals that he's a Half-Human Hybrid, as his mother is an elf.
  • Dragon Age II has Sebastian Vael, who is the spare to the spare as the youngest of three children. Initially he resented his brothers for this, but eventually he settled into life at the Chantry and was happy there. When his family gets slaughtered and Sebastian is suddenly the rightful ruler, he's not sure he wants to be prince anymore. Hawke can push him one way or another. In the end game, if Anders lives, Sebastian decides to take back his throne for real this time in order to exact vengeance. However, as the third game reveals, he takes the throne either way; he's just much friendlier if Anders is dead.
  • The Player Character of Dragon Age: Inquisition, if human, is in a similar position to Sebastian. Trevelyan's exact number of siblings is never stated, but it is known that they are the youngest of at least three. The family tradition thus dictated that they would join the Chantry, most likely as a Templar presuming they didn't show magical abilities themselves. Unlike Sebastian, since Trevelyan is the PC, the player has dialogue options which can show that they have a good relationship with their parents, a strained one, or something in between.
  • This trope also appears in the recent history of Orlais, as shown in an Inquisition codex entry. It was presumed that Emperor Judicael I's royal lineage would continue unhindered, as he was the father of twin boys. This was perfectly fine with Grand Duke Florian, his younger brother and spare, who never expected or wanted to rule; however, an outbreak of the Hundred Days' Cough killed both of Judicael's sons and also Florian's baby daughter. Judicael, grieving deeply, was thrown from his horse on a hunting expedition not long afterward, and Florian reluctantly became Emperor. This series of events paved the way for Judicael and Florian's niece, Celene, to eventually outmaneuver her cousin Gaspard for the throne, leading to the Orlesian civil war happening at the time of Inquisition.
• Dragon Quest:
  • Appears twice in Dragon Quest V:
    • Prince Harry's half-brother, Wilbur, never wanted to be king, but his mother orchestrates Harry's kidnapping, forcing Wilbur onto the throne so she can be Queen Dowager. When Harry returns ten years later, Wilbur is desperate to hand it over to him, and is completely stunned when Harry refuses.
    • In Gotha, Albert only rose to the throne after his elder brother disappeared; though he has done a far better job than Wilbur, he's still a Reluctant Ruler who immediately tries to hand the reins over to the just-arrived heir, despite the fact that his newly rediscovered nephew has only just learned of his Secret Legacy and has had about zero training as a ruler.
  • Dragon Quest VIII has a similar situation with King Argonia, an Unexpected Successor who had to step up after his elder brother disappeared while pursuing his lost love. While he has shaped up to be a good ruler, his own son is none other than Prince Charmles, causing his father no end of grief over how horrible he would be once it's time for him to hand down the crown. In the Golden Ending, he's presented with his brother's son at a rather awkward time for a family reunion, and it's heavily implied he cedes the right to rule after him to this new arrival, giving his own son the shaft.
• The Elder Scrolls:
  • From the series' backstory is Rislav the Righteous, detailed in the in-game book Rislav the Righteous. The titular Rislav was the fourth son in line to the Kingdom of Skingrad. His older brother, Dorald, was another spare who was allowed to follow his dream to become a priest of the Alessian Order, a radical religious movement sweeping the Empire at the time. When Rislav was 30, a plague swept through Cyrodiil and decimated the royal family of Skingrad. Only Rislav and Dorald survived. The throne fell to Dorald, who immediately ceded the kingdom to the Alessian Empire. Incensed, Rislav gathered a band of cavalry, rode for Skingrad, was allowed in without conflict by the city guards (who were equally upset at Dorald's actions), and beheaded Dorald. Rislav was quickly named King of Skingrad. However, Emperor Goreous (a fervent supporter of the Alessian Order) did not recognize Rislav and did not revoke Dorald's action. He rode with an army to Skingrad but was defeated by Rislav and his Colovian troops. It marked the beginning of the end of the Alessian Empire and the Alessian Order.
  • Martin Septim was a spare crossing over with Hidden Backup Prince. The bastard son of Emperor Uriel Septim VII, he was ferried away to a farm couple and later became a priest of Akatosh. When the Mythic Dawn assassinated Uriel VII and his legitimate heirs to kick off the Oblivion Crisis, Martin's actual parentage was revealed to him and his actions to end the crisis saved all of Tamriel.
• Fire Emblem:
  • In Fire Emblem: Radiant Dawn, it's eventually revealed that Sanaki is actually this trope; she had an older sister who was the true apostle and the rightful empress of Begnion, but said sister and their grandmother were assassinated by the Begnion Senate so they could frame the herons, leading to the Serenes Massacre. In a double subversion, said sister (Micaiah) turns out to have survived the assassination, but abdicates the Begnion throne to go rule Daein in the end.
  • In Fire Emblem: Awakening, main protagonist Chrom is perfectly content to lead his wandering peacekeeping force, the Shepherds, while his older sister, Exalt Emmeryn, rules the country. Chrom loves and admires Emmeryn, and gives her nothing more than a token "This isn't what I would do" when he disagrees with her decisions, but nevertheless carries out her will. So when she catches a faceful of Plotline Death and he's suddenly in her place, he's devastated. In fact, his Kid from the Future makes her first attempt to Set Right What Once Went Wrong by preventing Emmeryn's assassination, and thus preventing Chrom from ever being Exalt. Unfortunately for Chrom, she still died, just in a different circumstance. (The player can later find out she survived with amnesia, but this is an optional mission and it does not change anything, practically speaking. Chrom is still Exalt because she can't be.)
  • In Fire Emblem Fates:
    • At the end of the Birthright route, Crown Prince Xander of Nohr is killed in battle and second-in-line Camilla abdicates, leaving Leo to take the Nohrian throne.
    • At the end of the Conquest route, High Prince Ryoma of Hoshido and his second-in-line Takumi are killed in battle, leaving Hinoka to take the Hoshidan throne.
  • At the end of Fire Emblem Heroes Book II, Surtr and his heir apparent Laegjarn are killed in battle, leaving his second daughter Laevatein to take the Múspell throne.
  • Fire Emblem: Three Houses: Edelgard was born the ninth child of Adrestia's emperor and thus considered unlikely to inherit the throne. However, the deaths of all of her siblings leave her as the last remaining heir by the start of the game.
  • Fire Emblem Engage:
    • Alcryst is the second prince of Brodia, while his older brother Diamant receives far more attention within the game. This leaves Alcryst with a massive inferiority complex despite enjoying warm relationships with his father and brother. When Morion asks about the possibility of Diamant dying in battle and leaving him to take the throne, Alcryst is visibly distressed over this prospect, but firmly resolves he will not let it happen.
    • Inverted with Princess Céline of Firene, who explains in one of her supports that due to her older brother Alfred suffering from chronic illness during their childhood, she was trained as though she were the heir in case he died, only for him to eventually recover. If Alfred isn't S-Supported, he will die young in the epilogue, leaving Céline to take the throne (unless she dies on Classic Mode).
• Pops up a few times in League of Legends.
  • Azir was the youngest of all his siblings, and was completely ignored by his father as a result. Then all of his brothers were assassinated, and Azir soon found himself Emperor of Shurima after his father's death. A quite beloved and famed Emperor on that.
  • Just a hop from Shurima is Ixtal, and their royal line. The spare of spares being Qiyana, the youngest of 10 sisters. Qiyana is well aware of her minute chances of being ruler, and as such has been scheming past, plotting behind and outright crippling her siblings to make sure she inherits the throne.
  • The Ruined King, AKA Viego, was the back-up plan for the ancient, long forgotten kingdom he hailed from. He ascended to the throne after his older brother died, and quickly ran the kingdom into the ground.
• In Reflections on the River, Prince Shun was adopted essentially for that purpose. The king and queen weren't sure that they'd ever be able to have children of their own, so arranged to adopt a prince from an allied kingdom — but now they do have their own child, and Shun became the backup. He doesn't hold any grudges against the new heir, but he does feel useless and unappreciated, as he's not allowed to ever do anything useful — he just has to hang around in idleness until they're sure he won't be needed.
• Suikoden V has a non-royal example with the House of Barows. After his older brother Hiram was assassinated during the bloody Succession Conflict, Euram was thrust into the role of his father's heir, as well as dealing with his mother's extended BSOD. This stress of this helps shape him into the irritating Epic Failing Upper-Class Twit everyone has to deal with during the events of the game, until Character Development enables him to grow out of it.
• In Triangle Strategy, Prince Roland of Glenbrook is initially this, as he's the younger brother of Crown Prince Frani. At the start of the game, he enjoys relative freedom to do whatever he wants, whenever he wants. This changes after Aesfrost invades Glenbrook — Frani dies trying to protect Roland, and his father, King Regna, is executed just days later. As a result, Roland ascends to the throne and gets gradually worn down by The Chains of Commanding.
• Yakuza 6; it's revealed near the end of the second act that Yuta Usami is the second son of Big Lo, the leader of the Saio Triad that has been muscling in on Kamurocho. Due to China's One Child policy, Yuta was born off record and smuggled to Japan as an insurance policy in case Lo's eldest son died, raised in ignorance of his heritage so he wouldn't get any ideas and start a Sucession Crisis. When he does learn this, he also learns he fathered a half-Japanese son that the Saio Triad has been attempting to murder, and isn't in any mood to take his role as heir.
• Warhammer 40,000: Rogue Trader starts with the player character having been so recently brought on board the von Valancius flagship to serve as a a spare to the position of heir to the Rogue Trader that you haven't actually been briefed yet (the plan is that you'll serve as an advisor and close aide, and if nothing happens to the designated heir you'll continue to do so for them when/if they become Rogue Trader). By the time the prologue is over, both the Rogue Trader and all other known possible heirs are dead or unsuitable by way of treason and Chaotic heresy, leaving you as the new Rogue Trader.

• Disenchantment: Zog was actually second in line to become king and never expected, nor desired, to get the title, but was forced to take it anyway when his older brother unexpectedly died. It's the main reason he is so bad at being a king, and he is well aware of it.
• Skeleton Warriors: When Grimskull's pre-Heel-Face Turn crime becomes publicly known, the people of Luminicity want him to be executed for this and the only way his brother can spare him without having to face a revolt is by being executed in his place. With Lightstar dead and Grimskull still being labeled a traitor, their sister will be the next in line to become the ruler of Luminicity regardless of the fact she never received any training for this. Fortunately, Grimskull earns forgiveness on time to prevent any executions from happening.
• Voltron: Legendary Defender uses this trope in regards to none other than Prince Lotor. He's conspicuously absent from and uninvolved with his father King Zarkon's campaign for galactic conquest, and is only brought back into the fold after Zarkon is defeated by the Paladins during the Season 2 finale; prior to that, despite being the sole heir to the Galra Empire, the soldiers don't seem to know who he is.