Transhuman Treachery

Part of the Horror of being infected by The Virus is its ability to corrupt the mind of a victim, subordinating them into a Hive Mind or outright making them a sociopathic shell of their former self, intent only on killing or infecting their former loved ones.

But then there's times that a transformation doesn't brainwash, de-soul, drive insane, or demonically possess the victim. Other times the Viral Transformation causes changes that are purely cosmetic, granting amazing abilities albeit at great cost and (usually) a horrifying appearance. So what do these unwilling tranformees do? Become Phlebotinum Rebels or Vampire Refugees and use their powers to fight these monsters? Nope. They engage in Transhuman Treachery.

They sell out humanity and ally with who- or what-ever did this to them, regardless of whether or not they wanted to kill all vampires, robots, mutants, or aliens five minutes ago. There is no shock, only joy at becoming "more" than human and being able to flout society's rules.

If this Face Heel Turn is too quick, it gives the impression that one of the other things is going, like The Dark Side, or With Great Power Comes Great Insanity. However; this trope may be justified a couple of ways. If The Mind Is a Plaything of the Body it doesn't matter that vampire Dan doesn't want to drink human blood, he has to, and trying to be friendly won't last. If the setting has an ongoing "race war" against what the character has become, if they don't join their new race they'll quickly face death. However most of the time the switch in alliances comes about with alarming speed and lack of concern. At best you'll see these Big Bad Friends offer the transformation to a friend or loved one... and kill them if they refuse. The Dark Side, they have cookies.

It seems resisting these new biological impulses or avoiding becoming drunk on power is reserved solely for protagonists with Heroic Willpower.

A possible cause of Beware the Superman, this is the third sin in the Scale of Scientific Sins. Compare Sheep in Wolf's Clothing. Contrast Monsters Anonymous. May lead to forming an Anti-Human Alliance. Opposite Tropes to Pro-Human Transhuman.

Anime

 * Vampire Hunter D: Being made a vampire in this world is like this, even for vampire hunters! In Bloodlust the eldest of the vampire hunting brothers is turned, and he instantly sides with Carmilla and threatens to kill a former associate by drinking her dry.
 * Possibly With Great Power Comes Great Insanity, thanks to what can happen with Dhampirs, or what happened in
 * Or in The Rose Princess
 * In fact, it gets a lampshading/explanation in Book 1...there's debate over whether someone being turned is murder, as the victim is still around, but the personality changes are severe.
 * Then again, books 1 and 2 mention a few times that vampire victims who hadn't been turned yet had more than their blood drained out of them, which would go a long way towards explaining things.
 * Darker than Black: Tania has a quick and jarring her personality shift upon becoming a Contractor. Originally, she was a kind person. She immediately becomes cold towards her friends and by the third episode is really enthusiastic about the idea of selling her friends out to an intelligence agency for a chance for promotion.  Making this example especially jarring is that there's several examples of Contractors who don't turn on their loved ones, which kind of makes you wonder why she became this way.
 * It is possible that kind people like Tania are actually more liable to immediately become the norm for Contractors when suddenly becoming detached from their emotions. Basically the human identity's emotions dictated their actions hence their Contractor identity's actions are unrecognizable.
 * Similar to the Vampire Hunter D example above, vampires spawned by other vampires in JoJo's Bizarre Adventure are all complete monsters. One scene ha a woman pleading with Dio to spare her baby, and he agrees, on the condition that he can drink her and turn her into a vampire. Immediately after the transformation, she tears her own baby apart.
 * In Blassreiter,  is infected with nanomachines and transforms into an Amalgam. Beatrice convinces him that this is a good thing, as only the Demoniacs will survive the coming Armageddon, and he sets to work infecting the rest of the XAT, all the while claiming it's for their own good.
 * Because every demon in Berserk was once human, there's a good amount of this going around in the general universe. The Godhand picks their own by demanding that the demon-to-be sacrifice whoever or whatever he or she most cares about. Once someone becomes a demon, they usually cast off their humanity and become Complete Monsters of the worst order, with many of them engaging in eating their former species and/or raping people on the side. There are exceptions to the general norm (Zodd, Locus, and some others), but many demons in Berserk are dedicated to spreading misery and suffering among humanity, which is exactly how the Godhand likes it. It does help that the humans chosen to become demons by the Godhand were picked specifically because they were the type most likely to accept the Godhand's offer.
 * A few of the turned people in Shiki, the most noticeable case is Megumi who gleefully torments her former friends when she arises as a shiki herself. Granted she didn't like the village when she was human but that was more of a spoiled brat personality. She goes into Complete Monster territory once she's turned.

Comic Books

 * Marvel Zombies: A disturbing example shows up. In the worst Mad Scientist fashion, after Reed Richards sees a zombie She Hulk eat his children he decides (after studying the zombies) that they are the next evolutionary step and turns the whole FF into flesh eating fiends! Also from the same book, Zombie Infectee Giant Man knocks out and hides Black Panther because he wants to have a "snack" to eat later, knowing his former colleagues would kill the world's population in days.  He survives, thankfully, and gets a new leg out of it.
 * In Evil Evolution
 * Zombie Spider-Man was hit with the business end of the Horror Hunger stick just as he got home to Mary Jane and Aunt May. Hilarity ensued.
 * Being vamped in 30 Days of Night pretty much instantly makes you a sociopath. To date only three people have had the moral strength to resist this, everyone else basically gives in to their inner jerk.
 * In Swamp Thing: The Curse (part of Alan Moore's run), a recently-vamped boy taunts one of his parents about how they were too ineffectual to protect him while he tears out the other's neck.
 * Transmetropolitan: Both ends of the spectrum are represented: Fred Christ's Half-Human Hybrid Gray aliens are all-too-quick to embrace their newly-bought alien side and their role as a vengeful, oppressed minority. On the other hand, Tico and other "foglets" are living it up as nanomachine clouds, holding no ill will towards mankind.
 * To be fair, the Transients (the half-aliens) are explicitly said to draw most of their recruits from humans who already have alienation issues.
 * Averted in X-Men #2. It's made abundantly clear in the text that, despite this trope appearing to be in play, there is definitely brainwashing in play, at the least More Than Mind Control.
 * Then played straight later-on, when people are turned in the traditional way.
 * Lucy Westerna in the DC comic Victorian Undead 2: Sherlock Holmes vs Dracula. In this alternate version of Dracula, she avoids being staked upon her awakening after being turned and sides with Dracula to takes over London. Going on and on to the protagonists how she likes the power that being a vampire has given her

Film

 * Averted in Let the Right One In. Eli feeds on people, and will often use the fact that she's looks like a 12-13 year old girl to appear harmless. However, she clearly does not enjoy doing it and only does so when she can no longer resist the hunger. After her first shown attack in the film she looks like she's about to cry afterwards. The only time she deliberately unleashes death is  This clearly hits her Berserk Button and launches an Unstoppable Rage.
 * Blade: Pretty much every vampire in the trilogy, whether five minutes or five centuries old is invariably fine with messily killing humans. The handful of exceptions were all cured with an anti-vampire drug, and of course Blade himself (being a Daywalker) is the big exception.
 * Only because he hates vampires even more than people, though. It's mentioned in the films that he survived by killing and draining homeless people before meeting Whistler (nothing much is made of that, because the homeless obviously aren't real people.)
 * Though any movie with still sentient zombies has this, The Return Of The Living Dead shows how Freddy 'has an epiphany' that the only thing that can stop his pain and will show Tina's true love for him, is letting him eat her delicious brains.
 * The hemophages in Ultraviolet follow the "race war" scenario.
 * The humans don't even give them a chance. At the beginning, two investigators arrive to the scene of the crime, where a hemophage's body can be seen. One of them accidentally touches the blood. Two seconds later, his partner pulls out a gun and puts a bullet in his head (which is, of course, ignoring the fact that he's bound to get some of his partner's blood on him).
 * A heroic example occurs in Avatar. As Jake gets used to his new body, he also shifts loyalties towards the alien race, and he eventually leads them to war against the humans. And by the end, . So do all the other Avatars, for that matter.
 * Anyone bitten in the From Dusk till Dawn series. The infection is more akin to a zombie bite and once the victim turns, the only thing on their mind is attacking anyone human for their blood (which is a very messy process since these vampires tend to rip off limbs) or bring into their ranks.
 * Some variation of this seems to be part of Magneto's plan to  in the first X-Men movie.
 * In the Count Yorga movies all the turned victims instantly become evil and obey Yorga without question examples being Erica, who attacks Hayes along with the other brides, tries to attack Michael when he comes across the dying Hayes (and yet oddly gives him a chance to stake her, he doesn't go through with it) and attacking Michael and Donna as they're leaving right after  who likewise attacks Dr. Hayes with the other brides. An unused scene also showcased she had become monstrous enough to eat a baby..
 * In the sequel, theres the Cynthia's sister, Ellen, who joins Yorga's brides after his harem attack their family. She, along with the other brides, torments Cynthia mentally as she trying to find her way out of Yorga's mansion. She is also part of an ambush on her boyfriend which results in him killed and thrown to the vampire brides for food (of which Ellen joins in on).
 * Lillian and Mara in the first film of the Subspecies. Mara is the first victim of Radu's, after being buried and rising as an undead later, helps Radu lure out her friend Michelle and capture her. Lillian is kidnapped in the middle of the film and slowly turned by Radu. We actually see her becoming a monster as her transformation finishes while Michelle and she are trying to escape Radu's castle. Lillian instantly turns on Michelle once her fangs form, scaring her right into the arms of Mara. The next scene sees the two dragging Michelle to Radu so he can bite her and even smiling wickedly as they hold her down so she can't escape, pretty much solidifying their loss of humanity.
 * Very frequent in the Hammer Horror Dracula films
 * Horror of Dracula: Lucy, after becoming a vampire, preys on her niece as one of her first victims.
 * The Brides of Dracula: A village girl and a school teacher, Gina, fall victim to the vampire Baron and instantly become evil upon resurrecting.
 * Dracula Prince of Darkness: Helen, the protagonist's sister in law, tries to attack her two remaining family upon becoming undead.
 * Taste The Blood of Dracula: Another character named Lucy is turned and helps Dracula and her hypnotized friend killed her father and later bites her boyfriend.
 * The Satanic Rites of Dracula: All the women in Dracula's cellar were once agents investigating the cult a company had ties with and were captured and turned. In the film we see the secretary of one of the agents, Jane, kidnapped herself and turned by Dracula. When Jessica discovers her in the cellar and tries to free her. Jane bears her fangs and tries to bite her, helping the vampire women knock her down so they can feed on her. She also tries to pull the same trick on her boss as well.
 * In Dracula 2000, gives us the three Dracula's brides of the film. While the first two are somewhat dubious (Solina was a thief as a human and seem to gleefully relish being a vampire. We don't know much about Valrie as she just a reporter in the wrong place at the wrong time). Lucy fits the trope well as she was a roomate of Drac's main target Mary and the two got along well. Once she was turned however, she had no reservations on attacking Mary with the other two brides.

Literature

 * Usually averted by Alastair Reynolds, but his most recent Revelation Space prequel, The Prefect, includes
 * In The Dresden Files all the vampire courts appear to have this to a greater or lesser degree. When the Red Court fully transform the human part of them dies entirely, though the physical form is still used as a "flesh mask" by the creature within. However they don't cross over until they kill a human and their blood, and several members of the organization dedicated to fighting the Red Court are Vampire Refugees. The Black Court are Dracula style vampires, but little is mentioned about how they reproduce except that they do it fast, which does imply a pretty complete transformation. The White Court are the least hit by it. They end up sharing their body with a demonic Hunger that heavily influences them, but it is possible to fight against it. They're also a family, so it's more a matter of accepting the family business than a 180 degree allegiance switch.
 * In Known Space if an hominid above a certain age eats from the Tree of Life it becomes a Protector where they enter true adulthood and have a massive amount of changes, making it stronger, faster, more resistant to damage, and granting it super-human intelligence. A Protector is compelled to protect his genetic lineage, and his species from any possible harm. As a matter of course, Protectors exterminate any nearby alien species on the grounds that they might become a threat.
 * Most Protectors are only interested in protecting their direct descendants and are perfectly willing to nuke other human groups to do so. It's a rare Protector who can make itself feel concerned for humanity as a whole, and usually only when all of its own lineage has been killed off.
 * Inverted in The Vampire Files with, who'd actually been prone to rape and murder women while drugged out of his mind prior to becoming a vampire. His transformation rendered him unable to do drugs anymore, and brain trauma suffered when he died stripped away his memories of his past misdeeds and their motives, allowing him to achieve a Heel Face Turn because he'd ceased being human.
 * In Oleg Divov's Brothers in Reason, the Big Bad turns out to be . Subverted in that.
 * In James H. Schmitz's “The Machmen”, the machmen claim this is the case, but the protagonist believes they are merely being brainwashed as well as enhanced.
 * Inverted by Myria Lejean in Thief of Time: rather than a human made into a monster choosing to be a monster, she is something inhuman made into a human that ends up choosing humanity's side. (Humanity Is Infectious, but the other incarnating Auditors merely go insane from it).

Live Action TV

 * Lauren on Being Human (UK) is less than humane. Mitchell transformed her into a vampire to "save her" from dying when he fed from her and has regretted it ever since, not least because the once sweet and kind Lauren has taken to her vampiric biological mandate with gusto and sociopathy. It remains to be see whether she changes her mind or doesn't get killed first.
 * In episode 5, Lauren
 * Herrick has put some thought into this trope, and decided that evil isn't the answer, it's the moral imperative.
 * Buffy the Vampire Slayer: One of Riley's friends gets hybridized with demon body parts by Adam against his will. Despite being a trained and loyal soldier involved in a demon hunting/capturing program, he completely switches sides after the operation because he liked the power.
 * And had mind control chips in his head.
 * Not to mention dead and re-animated.
 * And, of course, all the vampires. Instantly. Although "you're not looking at your friend. You're looking at the thing that killed him," is the official story from the start, this gets...layered over time. Because vampires may have had their souls replaced by demons and a complete moral rewrite, but they still have the same memory set, and in some cases this hits harder than others.
 * For example, Darla in the flashbacks on Angel was quite pleased with Liam Angelus' decision to kill off his entire hometown to one-up her suggestion that he do the normal thing and kill his loved ones. After he got to his family, she took great pleasure in pointing out how yes, he was evil now, but he was still him, and now his father could never approve of him, being dead. This hit home.
 * And William/Spike does exactly this, and there's Vampire Willow. Theories exist that the vampire character derives from everything suppressed by the original human, but this only applies in some cases. Harmony, for example, starts killing people and decides she wants to be some kind of dark lord, but honestly doesn't change at all. It probably has something to do with self-image. People with low self-esteem seem to change more, but the completely pathetic seem to stay pathetic. That Liam and William seemed like losers but turned into Badass vampires probably indicates that they had Hidden Depths.
 * On the other hand, when Giles is turned into a Fyarl demon by Ethan Rayne in an evil prank meant to get him killed, he barely changes at all, apart from a gag while he's in the car with Spike, who's the only guy around who speaks Fyarl.
 * Doyle went through a huge personal crisis when he found out he was half-demon and started being able to change, and he did go from an upstanding third-grade-teacher married to a woman he met volunteering at a soup kitchen to a faintly skeezy always-in-debt skater around the edges of legality in the demon side of L.A., but that wasn't his heritage. Just his emotional reaction.
 * In the final season of Earth: Final Conflict the Atavus are introduced. They feed on human Life Energy and in so doing make those fed on human/atavus hybrids who in turn must feed on others, repeating the process. Even Plucky Comic Relief tech girl is unable to resist the urges.
 * On Supernatural, all the Psychic Children we meet who aren't killed before they can turn their demon-blood-born power toward Azazel's murderous expectations. Jake even kills Sam and unleashes hell on earth, intending to lead an army of demons against humanity.
 * Gordon Walker was already an antagonist before he got turned into a vampire, with the goal of killing Sam because he believed Sam was the Anti Christ and would lead hell's army against humanity. While a turned Gordan (says he) planned to kill himself after killing Sam, along the way he killed to feed, killed newly-made vampires, killed the hunter he was working with, nearly killed Dean, and turned a young woman as a distraction.
 * The Synthetics in Odyssey 5 are either completely synthetically grown Artificial Humans or nanomachine enhanced humans. The latter have to obey the A Is which created the nanites, being even part of a low-grade Hive Mind; however Chuck Taggart reveals after reversing his assimilation that the process can't completely subsume a human unless they want it to. The terrifying implication being that those humans infected want to serve the genocidal AIs.
 * When discovered she was a Cylon on Battlestar Galactica Reimagined, in contrast to, who went all What Have I Become?, it didn't take her long to start seeing the benefits of it and how it meant she was 'better' than humanity, something the ordinary Cylons no longer really boast about anymore though they did use to. She even advised actions that would likely have caused thousands of humans to die in the mid season finale. All of which makes little sense given the Cylons she was with were actually in a weaker position than the humans at that point. In light of what happened later, maybe she should have waited a while before throwing her eggs into another basket.
 * Done several times on Doctor Who.
 * Evil industrialist and Diabolical Mastermind Tobias Vaughn from "The Invasion" has undergone partial cyber-conversion by the Cybermen but retains his emotions and appears outwardly human.
 * In "The Next Doctor", the Cybermen attempt to make their collaborator Miss Hartigan their "King", but she turns out to be exceptionally strong-willed - while most of her morality gets discarded, she retains her emotions and is able to take control of the Cybermen's Hive Mind. The Doctor defeats her by
 * Somewhat annoying, as she was evil before her Cyberconversion, and seemed the sort of person who would have loved the opportunity to pilot a Steampunk Humongous Mecha through London.
 * Hardly. At the start of the episode (the first time we saw her) she already appeared to have been tampered with a little. We never saw her 'original' personality.
 * In the Ark in Space, one of the crew gets infected by the Wirrn, and is turned into one of them. He's also the one that causes the ship to blow up be after the Doctor tampered with it, and he theorizes he must've had just enough humanity left in him to resist the Wirrn's hive mind.

Tabletop Games

 * Clan Tzimisce of Vampire: The Masquerade deserves special mention; all vampires in the setting suffer from humanity degeneration, but the Tzimisce have explicitly become transhumanists after developing Vicissitude. They tend to lose their humanity quite a bit faster than average.
 * Then again, that's partially due to the general WTFery of Clan Tzimisce, and partially due to their membership in the Sabbat. The Sabbat truly, honestly believe that vampires are better than humanity, and have the right to rule over the "cattle" as they see fit. This often involves chainsaws and crime sprees amongst the younger Kindred, and utterly alien moral codes amongst the elders.
 * Humans vs. Zombies breathes this trope; once tagged, you become a Zombie, and you need to feed. Of course, that doesn't mean you still can't have a vendetta against the other humans who were less than helpful in keeping you safe...

Video Games

 * Starcraft: Kerrigan is Queen Bitch of this trope. At first she's somewhat mind controlled, yes, but also fairly autonomous. And then she's entirely autonomous and sells out the human race to lead the Zerg. She seemed slightly sad about trying to kill Raynor out but she got better. Apparently tied to the very nasty mental conditioning and childhood she had.
 * When she infests, he becomes an intelligent and fairly free-willed (and she knows it, so she threatens him if he ever turns against her). He immediately falls in love in her and follows her orders and does everything to gain her approval.   Starcraft2 goes into a bit more detail, and the Zerg Campaign will likely go into more...
 * Subverted in BioForge. The Mad Scientist hoped this trope would come into play after he upgraded (and deformed) you, but instead made you into a vengeful Phlebotinum Rebel.
 * Ironically, the protagonist still becomes what he hates in the process. He loathes them for trying to turn him into a murderously deranged cyborg... and by the end, he has become just that—only directed at his creators, casually killing anyone even slightly related to his capture and transformation.
 * Half-Life 2: The Transhuman Arm of the Combine Overwatch combine this with being Les Collaborateurs. Humans start out joining Civil Protection to get decent rations; promotions are tied to voluntary brainwashing until they become eligible for Mind Rape and modification into actual transhumans (though the Combine often picks up random civilians for conversion too). Soldiers presumably go through the same rank system with the highest-ranking Elites being more like synths than cyborgs.
 * Mass Effect 3: Javik explains that this happened to a species during his time: the Zha'til. They resorted to cybernetic implants to improve themselves, and wound up being controlled by the implants and changing into a synthetic race which waged war on the rest of the galaxy. They are one of the main reasons Javik hates AI's so much.
 * Pokémon Black and White, of all things, has this in the Yamask-Cofagrigus family. Yamask Was Once a Man and carries a mask of its former human face, which it sometimes cries over. By the time it evolves into Cofagrigus, it begins seeking to capture and convert humans into more Yamask.

Webcomics

 * Charby the Vampirate: Charby once explained that this effect is there to keep a new vampire from immediately turning around and using his/her powers against the one that sired them. It doesn't last forever and can be overcome by sufficient willpower, but in some cases it's More Than Mind Control.
 * It explained it again.
 * Brock from Braceface Fangface and Brock of the Undead. Despite now being a walking corpse that must feed on blood who must obey his new master. The power more then outweighs the negetives and he happyily uses it to bite his girlfriend, Maria, and bring her into the ranks of the undead.

Web Original

 * In the Metamor City podcast novel Making The Cut, this happens to  after she's turned into a vampire. The vampires order her (which cannot be disobeyed) to not kill herself, do anything against them, lie to them, and she has to operate as a spy for them. They eliminate every possible option for rebellion/escape, or letting her Psi Collective people know what happened to her in any way.
 * The Jonathan Coulton song "Re: Your Brains" has this as its central premise, with the singer using office lingo while attempting to talk a (former) co-worker into allowing himself and the other zombies in to eat the survivors' brains.
 * In the site Vamp You, all vampire transformations work like this. Anyone who is turned, gets a villain card.

Western Animation

 * Inverted with the Pack in Gargoyles. When Coyote, a robot, offers various "upgrades" to the other members, Jackal and Hyena become HollywoodCyborgs and Wolf becomes a Half-Human Hybrid. Dingo, the group's Only Sane Man, forgoes the transhumanism, takes a suit of Powered Armor, and would later make a Heel Face Turn.