History Main / HybridOverkillAvoidance

*** One exception is a [[TabletopGame/VampireTheMasquerade vampire]]-[[TabletopGame/WerewolfTheApocalypse werewolf]] hybrid "abomination," extremely tricky but possible. Werewolves are violently allergic to vampire blood so if you try to 'embrace' one, he gets a roll to see if he died peacefully or in horrible pain. Unless they're out of all Willpower, they get to die automatically. A hybrid is created only if you [[CriticalFailure botch]] that roll. A hybrid does have access to all the powers of both but has to watch the KarmaMeter very carefully - from a spiritual point of view, werewolves and vampires are pretty much opposites (one being a nature spirit that just happens to have flesh while the other is a dead shell with barely any spiritual presence) so straining too far will be detrimental to all spirit-related powers. Their Gnosis now functions like a normal vampire's Humanity and goes down from actions unbecoming of a Garou. They retain their old Gifts but can no longer learn any new ones except from corruption spirits. And if their Gnosis runs out, they go into a mindless rage until someone or something inevitably puts them down. That's if they get to that point, of course - plenty of both vampires and werewolves will put them down just for existing.

*** One exception is a [[TabletopGame/VampireTheMasquerade vampire]]-[[TabletopGame/WerewolfTheApocalypse werewolf]] hybrid "abomination," extremely tricky but possible. Werewolves are violently allergic to vampire blood so if you try to 'embrace' one, he gets a roll to see if he died peacefully or in horrible pain. Unless they're out of all Willpower, they get to die automatically. A hybrid is created only if you [[CriticalFailure botch]] that roll. A hybrid does have access to all the powers of both but has to watch the KarmaMeter very carefully - from a spiritual point of view, werewolves and vampires are pretty much opposites (one being a nature spirit that just happens to have flesh while the other is a dead shell with barely any spiritual presence) so straining too far will be detrimental to all spirit-related powers. Their Gnosis now functions like a normal vampire's Humanity and goes down from actions unbecoming of a Garou. They retain their old Gifts but can no longer learn any new ones except from corruption spirits. And if their Gnosis runs out, they go into a mindless rage until someone or something inevitably puts them down.

*** One exception is a [[TabletopGame/VampireTheMasquerade vampire]]-[[TabletopGame/WerewolfTheApocalypse werewolf]] hybrid "abomination," extremely tricky but possible. Werewolves are violently allergic to vampire blood so if you try to 'embrace' one, he gets a roll to see if he died peacefully or in horrible pain. Unless they're out of all Willpower, they get to die automatically. A hybrid is created only if you [[CriticalFailure botch]] that roll. A hybrid does have access to all the powers of both but has to watch the KarmaMeter very carefully - from a spiritual point of view, werewolves and vampires are pretty much opposites (one being a nature spirit that just happens to have flesh while the other is a dead shell with barely any spiritual presence) so straining too far will be detrimental to all spirit-related powers. They can't learn any new Gifts except from corruption spirits. And if it runs out, they go into a mindless rage until someone or something puts them down.

* In ''TabletopGame/HcSvntDracones'' [[BeastMan Vectors]] have "mutt-reduction protocols" written into their genomes that normally allow different species to interbreed without hybridizing, instead producing offspring of [[RandomSpeciesOffspring one species or the other]]. But on rare occasions hybrids are produced, and are almost always sterile.

*** One exception is a [[TabletopGame/VampireTheMasquerade vampire]]-[[TabletopGame/WerewolfTheApocalypse werewolf]] hybrid "abomination," extremely tricky but possible. Werewolves are violently allergic to vampire blood so if you try to 'embrace' one, he gets a roll to see if he died peacefully or in horrible pain. Unless they're out of all Willpower, they get to die automatically. A hybrid is created only if you [[CriticalFailure botch]] that roll. A hybrid does have access to all the powers of both but has to watch the KarmaMeter very carefully - from a spiritual point of view, werewolves and vampires are pretty much opposites (one being a nature spirit that just happens to have flesh while the other is a dead shell with barely any spiritual presence) so straining too far will be detrimental to all spirit-related powers. And they can't learn any new Gifts except from corruption spirits.

*** One exception is a [[TabletopGame/VampireTheMasquerade vampire]]-[[TabletopGame/WerewolfTheApocalypse werewolf]] hybrid "abomination," extremely tricky but possible. Werewolves are violently allergic to vampire blood so if you try to 'embrace' one, he gets a roll to see if he died peacefully or in horrible pain. Unless they're out of all Willpower, they get to die automatically. A hybrid is created only if you [[CriticalFailure botch]] that roll. A hybrid does have access to all the powers but has to watch the KarmaMeter very carefully - from a spiritual point of view, werewolves and vampires are pretty much opposites (one being a nature spirit that just happens to have flesh while the other is a dead shell with barely any spiritual presence) so straining too far will be detrimental to all spirit-related powers. And they can't learn any new Gifts except from corruption spirits.

* Many real-life hybrids (mules, hinnies, zorses etc.) are themselves sterile. With big cat hybrids, this is actually {{Zigzagged}}: while male hybrids are sterile, some females can be fertile and produce UnevenHybrid offspring with either of their parent species. Hybrids of the common bottlenose dolphin and false killer whale are also fertile, as are dog, wolf and coyote hybrids.

* Most real life hybrids (mules etc.) are themselves sterile.

* In ''Series/BuffyTheVampireSlayer'', the titular Slayer is considered a human monster by some (having been infected with demonic power by the Shadowmen, the first Watchers). In one episode, while Sunnydale is caught inside a boy's psychic nightmares, Buffy is temporarily turned into a vampire, making her a Slayer/vampire hybrid and more than twice as strong as either is shown to be separately. However it's left unsure if this could happen in the "normal" course of events in the Buffyverse, as most vampires would prefer to kill a Slayer than turn her.

In a superhero setting, the trope expands to include 'super-origins' as well. A character's powers, however diverse, need a single unifying theme. Logically, if aliens ''and'' FunctionalMagic are real, there's no reason magic would be restricted to the one planet Earth and there must be [[WizardsFromOuterSpace alien magicians]] ''somewhere'' in the universe, but they won't appear as main characters. Undead who are bitten by radioactive hamsters don't manifest additional hamster-related powers: they just eat the hamster.

[[folder:Film]]

** The ''TabletopGame/OldWorldOfDarkness'' has similar rules to the above to prevent gratuitous crossover:

* The Jefferson Starships from ''{{Series/Supernatural}}'' were hybrids of various monsters that have appeared in the series. However, since they were unstable experiments created by [[BigBad Eve]], they had all died by the time they were encountered (and named) by Sam and Dean.
* In ''Series/TheVampireDiaries'' [[spoiler: this has been imposed on Klaus, who is a werewolf vampire. Because the resulting hybrid would be too powerful, witches cursed him to suppress his werewolf side, preventing him from transforming at the full moon. His goal is to break the curse, allowing him to create his own master race.]]

In a superhero setting, the trope expands to include 'super-origins' as well. A character's powers, however diverse, need a single unifying theme. Logically, if aliens ''and'' FunctionalMagic are real, there's no reason magic would be restricted to the one planet Earth and there must be [[WizardsFromOuterSpace alien magicians]] ''somewhere'', but they won't appear as main characters. Undead who are bitten by radioactive hamsters don't manifest additional hamster-related powers: they just eat the hamster.

In a superhero setting, the trope expands to include 'super-origins' as well. A character's powers, however diverse, need a single unifying theme. Logically, if aliens ''and'' FunctionalMagic are real, there must be [[WizardsFromOuterSpace alien magicians]] ''somewhere,'' but they won't appear as main characters. Undead who are bitten by radioactive hamsters don't manifest additional hamster-related powers: they just eat the hamster.

* In ''Series/BuffyTheVampireSlayer'', the titular Slayer is considered a human monster (having been infected with demonic power by the Shadowmen, the first Watchers). In one episode, while Sunnydale is caught inside a boy's psychic nightmares, Buffy is temporarily turned into a vampire, making her a Slayer/Vampire hybrid and more than twice as strong as either is shown to be separately. However it's left unsure if this could happen in the "normal" course of events in the Slayer 'verse, as most vampires would prefer to kill a Slayer than turn her.
** It's notable that a one shot episode villain in season 4 who easily beat Buffy was going to be explained away as a Vampire/Slayer hybrid, only to be cut for time and pacing.

*** Another exception is fomori, the fusion of a spirit of corruption with a material host. The most powerful of such spirits can pull it off on a supernatural host, specifically vampires, werewolves and most shifters, [[TabletopGame/MageTheAscension mages]], and [[TabletopGame/ChangelingTheDreaming changelings who've forgotten what they are]]. Long, long ago, the vampire Set spawned the dread [[TabletopGame/MummyTheResurrection Bane Mummies]] through corrupt magic, and found they had their own agenda; fortunately for everyone else, Set wisely decided not to try again, and no one else seems capable of it either. Most every other major supernatural is immune, including two of the Changing Breeds: the Corax were-ravens (thanks to their unique creation ritual) and the Nagah were-snakes (since they're a spiritual blind spot). And while being a fomori may offer the occasional benefit, they're far, far outweighed by the downsides.

*** Another exception is fomori, the fusion of a spirit of corruption with a material host. The most powerful of such spirits can pull it off on a supernatural host, specifically vampires, werewolves and most shifters, [[TabletopGame/MageTheAscension mages]], and [[TabletopGame/ChangelingTheDreaming changelings who've forgotten what they are]]. Long, long ago, the vampire Set spawned the dread [[TabletopGame/MummyTheResurrection Bane Mummies]] through corrupt magic, and found they had their own agenda; fortunately for everyone else, Set wisely decided not to try again, and no-one else seems capable of it either. Most every other major supernatural is immune, including two of the Changing Breeds: the Corax were-ravens (thanks to their unique creation ritual) and the Nagah were-snakes (since they're a spiritual blind spot). And while being a fomori may offer the occasional benefit, they're far, far outweighed by the downsides.

*** Only humans have avatars, so only humans can Awaken to become Mages. Becoming undead of any kind gets rid of the avatar, nixing that option. Shapeshifters were born as shapeshifters, even if they resemble humans or animals at birth, so they lack avatars. When they die they can't go to the same afterlife as human dead, so they can't become [[TabletopGame/WraithTheOblivion wraiths]], zombies, or TabletopGame/KindredOfTheEast.

* More justified than usual in the ''Literature/{{Shannara}}'' series. Although appearing to be a fairly generic high fantasy setting, it actually takes place in the distant future after a nuclear war. Most of the various fantasy races, including gnomes, dwarves and trolls, are actually mutated humans and not separate species.

Inside the story, this is usually {{justified|Trope}} (or at least given a decent HandWave) by having one supernatural/technological/biological "monster" or race be naturally [[TheImmune immune]] (or [[MadeOfExplodium violently]] [[WeaksauceWeakness allergic]]) to being hybridized with another. For example, a character who's been [[ViralTransformation changed]] into a werewolf can't be [[{{Mutant}} mutated]] with TheVirus since their HealingFactor protects them from further mutation. Robots won't become [[OurGhostsAreDifferent ghosts]] because, y'know, no [[OurSoulsAreDifferent Soul.]][[note]]{{Virtual Ghost}}s are doable, though.[[/note]] For whatever reason, in some settings characters can only change into one kind of supernatural critter, or only be one ''"at a time".''

* ''TabletopGame/TheWorldOfDarkness'' games enforce this trope for balance issues. Hypothetically though, any supernatural that can be changed back to human can be turned into another type.

* ''Manga/{{Bleach}}'': Quincies and Hollows are opposite existences to one another, enabling Quincies to utterly destroy Hollows instead of cleansing them like Soul Reapers do. On the flipside, Hollowfication empowers Soul Reapers but is extremely toxic to Quincies -- with only one known case surviving due to unique circumstances.

* ''Manga/{{Bleach}}: Quincies and Hollows are opposite existences to one another, enabling Quincies to utterly destroy Hollows instead of cleansing them like Soul Reapers do. On the flipside, Hollowfication empowers Soul Reapers but is extremely toxic to Quincies -- with only one known case surviving due to unique circumstances.

* In ''Anime/BNABrandNewAnimal'', while different species of BeastMan can procreate with each other, their children always belong to one of the parents' species - hybrids don't exist. [[spoiler:It later turns out that different kinds of Beastmen breeding results in offspring that are weaker. The BigBad is a pure blooded wolf beastman who wants to wipe out all of the beastmen with mixed ancestry because he sees them as inferior beings and not real beastmen.]]

%%** Directly averted in the NinjaPirateZombieRobot moment, in which Alternate!ComicBook/{{Morbius}} exclaims, "I am a VAMPIRE! I am a ZOMBIE! I am a [[BreadEggsBreadedEggs VAMBIE]]!"
** ComicBook/WerewolfByNight gets infected with the zombie virus, but because his biochemistry changes when he transforms the disease remains limited to his human form. So hitting the human zombie with magically created moonlight gives back a healthy (but feral) WolfMan.

** [[spoiler: Britt's Transformer form]] is effectively a [[NinjaPirateZombieRobot Ninja Vampire Zombie Robot]] (insofar as [[spoiler: CVO agents]] count as ninjas).

%%* Averted in the Literature/{{Xanth}} series in a several ways:

** In the lore, two race reproducing will result in a child with the race of the mother, with a few of the father's traits sprinkled in, such as a slightly taller Imperial due to an Altmer father. On its own the trope is played straight, but interbreeding over thousands of years between the Direnni Aldmer (biologically Altmer) and Nedic humans (essentially proto-Imperials) resulted in the magically talented but otherwise human Bretons.