When unable to care for their children, the best a parent can hope for is that they are raised by a trustworthy individual. This may be a kind stranger, but more often it is a dependable relative or close family friend. Sometimes, however, the opposite happens, and the child ends up in the care of the unimaginable: their parent's personal enemy.
Such arrangements are usually not voluntary, and typically follows the death, disappearance, or defeat of the parent, usually orchestrated by the rival themselves. A common scenario involves killing the parent but pitying the now-orphaned children, especially if the rival is meant to be viewed sympathetically. Other cases may be less altruistic, involving straight-up abduction or coercion. The child in question might be a hostage used as insurance or leverage against their family, while the most malevolent guardians — if they can be called that — actively strive to corrupt their ward out of spite or vengeance.
A character raised by their parent's rival is bound to experience Conflicting Loyalty at some point, especially if they have bonded with their guardian; in some instances, they may be the closest thing to family they can remember. Nevertheless, they will find it difficult to resist being drawn to their blood relatives. If the past is hidden from a young charge, they inevitably will discover the truth, and there will be a reckoning — especially if the guardian was responsible for their parents' demise.
Note that a rival guardian need not necessarily be a bad surrogate. Depending on the story, they may even be portrayed as a superior guardian who provides a better upbringing than the actual parents ever could. Less-benevolent guardians on the other hand may turn their ward into a Bastard Understudy that can fight effectively against their family, who may be reluctant to hurt one of their own.
- Dragon Ball: After Goku's death at the start of the Saiyan Saga, his son Gohan is cared for by his arch-rival Piccolo; it was Piccolo's full intention to keep Gohan forever when he first kidnapped him, but later saw him as a friend, essentially freeing him after a year. He later becomes something of an Honorary Uncle for Gohan, even after Goku comes back to life, and continues to take care of the saiyans' younger children at one point or another (Trunks, Goten, and Pan).
- My Hero Academia: After he murdered the seventh wielder of One For All, Big Bad All For One found her grandson and raised him to be his successor, knowing that the next wielder of One For All would be offended and hurt by the fate of the grandson of his beloved mentor.
- One Piece presents a rare consensual example: in the past, some time before the execution of Pirate King Gold Roger, he had a talk with his greatest rival, Marine Vice Admiral Garp, that he had a wife and would-be child, and he trusted Garp enough (being the man who had faced him numerous times in battle) to entrust them to him. Garp agreed to it, because he didn't want to disrespect Roger and he had a plan for the child himself, i.e trying to make him a Marine officer instead of a pirate. Garp would then help Roger's wife, Rouge, with hiding from the masses and witness her birthing her son.
- New Gods: An uneasy peace between New Genesis' Highfather and Apokolips' Darkseid (no points for guessing who is the good guy) is cemented by the two trading sons to be raised by the other. Darkseid's cruel parenting resulted in both sons hating him.
- Wildcat's son Jake was kidnapped by the villain Yellow Wasp. Ted spent decades searching for his son but only learned the truth decades after Jake had grown up and died without ever knowing who his true father was.
- A popular Fandom-Specific Plot in Harry Potter fanfiction is to have Severus Snape raise Harry after his parents die, even though Snape hated James Potter with a passion. The usual justification for this is that Snape is doing it to honor Lily's memory and/or to atone for the fact that he was indirectly responsible for their deaths.
- Attempted by Syndrome in The Incredibles. At the end of the film, he kidnaps Jack-Jack, declaring his intention to raise him as a sidekick, but this plan is thwarted in short order.
- In The Island (1980), after making Maynard a slave, Pirate King John David Nau takes Maynard's son Justin from him and starts raising him to become a pirate and his heir.
- In The Mask of Zorro, the daughter of the original Zorro, Don Diego, is kidnapped by his enemy Don Rafael as revenge. Rafael raises Elena as if his own daughter, loving her just as much. Part of his may be in memory of her mother Esperanza, who was loved by both Diego and Rafael.
- Thanos in the Marvel Cinematic Universe seems to make a habit of adopting children from the races he's devastated, and raising them as assassins. This includes Gamora, Nebula, and possibly the members of the Black Order.
- Star Wars The Rise Of Skywalker: This is revealed to be the case with Rey, the grandaughter of Darth Sidious/Emperor Palpatine, who was taken in by the Skywalker family, including Han, all of whom acted as a Surrogate Parent for her at one point in the sequels at least one of whom knew who they were. This most likely contributed to making sure she didn't wind up like her grandfather, and is reflected in the final scene when she calls herself "Rey Skywalker."
- In Holly Black's The Folk of the Air, the protagonist, Jude, and her sisters Taryn and Vivienne, are raised by the man who killed their mother and father (or stepfather, in Vivienne's case).
- Kushiel's Legacy: After Melisande, the Big Bad of the first two books, is imprisoned, her son Imriel is first raised by monks, then fostered by the heroine Phédre and her lover Joscelin. It's a surprisingly happy arrangement: Phédre and Joscelin love Imriel as a son, Imriel reciprocates, and Melisande trusts her Worthy Opponent to raise Imriel well.
- Theon Greyjoy of A Song of Ice and Fire was a child of ten when he became a ward of House Stark, held as a hostage to deter a second rebellion by his father, Balon. Brought up in Winterfell for nine years under the just hand of Eddard Stark, he returns home hoping to win his father's approval, only to be met with ridicule; the tension between these disparate identities drives his inner conflict and underlies many of his actions.
- In The Silmarillion, the twin children Elrond and Elros are taken in by Maedhros and Maglor, who in relentless pursuit of the silmaril assault a refugee settlement. During the bloodshed their mother Elwing is driven into the sea and only saved by Divine Intervention; she had already once fled the brothers in her youth, when they attacked the Kingdom of Doriath and killed her parents. Tolkien doesn't give many details on the twins' upbringing, save that it was apparently a happy one.
- Warrior Cats: Firestar takes Bramblepaw, the son of his enemy Tigerstar, on as his apprentice following his father's exile from the Clan and ensuing takeover of ShadowClan. Despite caring deeply about Bramblepaw, Firestar struggles to separate the innocent apprentice from his evil, look-alike father, something Bramblepaw notices and resents.
- In Worm, Amy Dallon, the teenage hero known as Panacea, is revealed to actually be the daughter of the villain Marquis. She was adopted by the superheroes Brandish (Carrol Dallon) and Flashbang (Mark Dallon) after they defeated and captured Marquis. He was sentenced to the Birdcage, an inescapable, life-sentence-only prison for villains, so this was tantamount to orphaning the infant Amy and they felt responsible. However, her presence in the Dallon family, combined with Mark and Carol's personality issues, led over time to major drama, heartbreak, and disaster.
- Hayven Celestia: After stabbing Kanti and leaving him for dead at the end of Small World, Saquel gets together with Kanti's pregnant mate Tish and raises his daughter Rahua as his own for a couple years until Kanti manages to establish contact with Tish again and explain who "killed" him.
- Angel: Vampiric Angel's infant son, Connor, is kidnapped and raised by zealous vampire hunter Holtz, who escapes to an alternate dimension and raises him as his own, turning him into a Laser-Guided Tyke-Bomb to eventually kill (and more importantly, hurt) Angel.
- Irisa from Defiance is an irathient raised by Nolan, formerly a Horrifying Hero who cheerfully massacred irathient tribes (including her own). He's mellowed out a lot since then, casting aside anti-alien prejudice and being a good father, but sometimes she still remembers how he raised her to be Hunter Of Her Own Kind.
- Ezel: Sekiz is brought up by Kenan Birkan, who ordered the death of his father when he was only a young boy, and used as a de facto hostage against his grandfather (and Kenan's enemy) Ramiz. Seeking Revenge Through Corruption, Kenan shapes Sekiz into a Bastard Understudy, making him believe his grandfather was responsible for the crime. His ultimate goal is to make Sekiz assassinate Ramiz, knowing the latter would not hurt his estranged grandchild.
- Arno from Assassin's Creed: Unity is the son of an Assassin raised by a Templar grandmaster. Both orders are ancient enemies, but Arno's birth father and adoptive father were friendly enemies. He's raised with no knowledge of either order, but winds up joining the Assassins anyway due to a twist of fate.
- Bioshock: In a loose sense of the word "raised", Jack, the protagonist and Andrew Ryan's son, was harvested and grown by Frank Fontaine in order to raise him into a Laser-Guided Tyke-Bomb to kill Ryan. Ryan's biological child would have an advantage doing this, as the Vita-Chambers were coded to resurrect Ryan and his immediate family.
- Far Cry Primal: After Takkar mortally wounds Ull, the chief of the rival Udam tribe, Ull begs him to look after his children (who will succumb to fatal illness if left in the care of other Udam). Takkar complies, and the ending shows they become valued members of his tribe.
- Final Fantasy Brave Exvius: Lasswell was raised by Raegen, younger adopted brother and rival to the Prince of Hess, Rowen, after Rowen was killed by errant monsters due to Raegen imprisoning him in a crystal. This depowered him and got him killed, leading to Raegen adopting Lasswell out of remorse.
- The entire premise of Fire Emblem Fates is that the protagonist, Corrin, was born in the kingdom of Hoshido, but was (for complicated reasons) raised by the royal family of Nohr, their rivals. As a Child of Two Worlds, the adult Corrin is now free to decide with which side to join in the ensuing war, justifying the two main routes of the game.
- Garou: Mark of the Wolves: Rock Howard, son of long-defeated Big Bad Geese Howard, is raised by the Fatal Fury series' hero Terry Bogard.
- Guilty Gear: Ky Kiske had a son with a Gear named Dizzy, Sol's own daughter of sorts. Since he was ruling a kingdom at the time the child was conceived, and Gears were still seen as threats by the world, Ky leaves his son to his longtime rival Sol Badguy's care.
- Kitana from the Mortal Kombat series. Shao Kahn, longtime pillager of her home realm of Edenia, killed her father, forcibly married her mother (she got out of it by committing suicide), and adopted her. Then made her a soldier, then tried to replace her with a homicidal clone for not living up to his expectations. He's quite a guy.
- Phoenix Wright: Ace Attorney: When the defense attorney Gregory Edgeworth was murdered, Manfred von Karma, a prosecutor he faced in court, took his son under his wing and trained him to become a ruthless prosecutor like himself. Manfred murdered Gregory for coming close to defeating him in court and giving him a penalty, but his revenge didn't stop there. By raising Miles to be more like himself than his own father, he almost twisted him into everything his father would have hated.
- Dan and Mab's Furry Adventures: After the dragon Hizell exterminated Fa'lina's clan, leaving her as the only survivor (and Cubi clan leaders are sterile), allies of hers managed to kidnap one of Hizell's children and brought him to her, and she decided to raise him as her own. Hizell now considers him dead.
- Teenage Mutant Ninja Turtles (2012): This eventually turns out to be the case with Karai, as she is not Shredder's daughter, but Splinter's. Years ago, when Karai (originally named Miwa) was a baby, Hamato Yoshi (Splinter) and Oroku Saki (Shredder) had a fight which led to their dojo being burned down, killing Yoshi's wife Tang Shen and trapping Yoshi inside, with a scorched Saki finding Miwa and deciding to raise her as his own child.
- Medieval European nobles would exchange their own children as hostages in order to guarantee good faith in peace negotiations. This could result in a child being completely raised by his father's enemies (though usually treated pretty well). Of course, this could have vastly different consequences from case to case:
- Richard I was raised by the French. Ultimately he came to identify more with them than with the English, and had barely seen his home country by the time he was king of it.
- Vlad the Impaler and his brother Radu were raised by Turks (his father wanted to secure an alliance against the Hungarians). Radu allegedly converted to Islam and fought as a general for the Turks, while Vlad would go on to cause a hell of a lot of problems for them.
- Andrew Jackson adopted a native American boy called Lyncoya, who was from a tribe that got massacred in a war with the US. Jackson might have felt sympathy for the boy because of his own past as an orphan, and apparently was fond enough of him that he tried to send him to West Point.