"Any character, after being gender bent, will come to enjoy their new gender more than their old gender."
A fictional character that gets his or her gender bent often becomes gradually accustomed to life as a new man or woman. Eventually they likely will experience an epiphany: that they are better off in their new gender than they ever were in their old one. This is the Second Law of Gender Bending, where a gender bent person would, if offered a chance to revert to their former gender, turn it down because they have come to enjoy the benefits of the change.
The epiphany typically takes one of two forms:
A reluctant admission, either because they've changed too much to return to the way things were or are loath to admit the enjoyment they get from their new lifestyle.
A jovial acceptance, where they quickly discover how much fun life is after the gender flip, and they never want to go back.
Kashimashi: Girl Meets Girl Hazumu never expresses any desire to return to her former gender. Of course, the aliens announced from the get-go that she couldn't become a boy again even if she wanted to, but you'd think she'd have missed something about life as a boy, even if it was only the ability to write her name in the snow. However, since the gender change allows her to get together with the girl(s) of her dreams and his/her parents seem to prefer it she really doesn't have all that much to complain about. (It doesn't hurt that pre-change Hazumu was more girly than every other girl in the series and may even have been transgender without realizing it.)
Averted in Ranma ½: Ranma never, ever, ever stops looking for a cure for his curse (except for one filler episode after he hits his head) though he does stop complaining about it. That said, Ranma starts to bring his macho approach to acting girly and cute. As seen in his competition with Tsubasa, Ranma's competitive streak is so hardwired that he even refuses to lose in a contest of femininity.
This doesn't stop him from exploiting the advantages of his female form for one minute, however.
Happens at the end of Cheeky Angel when Megumi finally realizes/admits that she'd been a girl all along: lacking the power to grant her wish to become male the trickster spirit had given her a purely mental Gender Bender instead. Since the delusion had helped her foster the tough, fair, forthright, and assertive (i.e., stereotypically "male") aspects of her personality Megumi considers her wish granted nonetheless.
The other transgender Megumi in The Day of Revolution goes the "reluctant admission" route when she's menaced by a boy and realizes that she finally knows how it truly feels to be a girl. Fortunately her new-found sense of femininity also empowers her to free herself with the ultimate female defence against male attackers: a Groin Attack so severe it practically paralyzes him.
Subverted in Sekirei. Homura deals with being a girl, but she doesn't like it and is obviously still uncomfortable with her growing attraction to her Designated Love Interest.
Played with in Switch! as when in heaven the protagonist can't decide whether to be a male or female angel.
Played with in Some Like It Hot. At first, Gerald doesn't like being Daphne. Dresses are too drafty, he can't hit on women, etc. Eventually, though, he enjoys being female immensely, to the point where the Ho Yay with Osgood is so great that Joe makes him say "I'm a boy," over and over. But hey — Nobody's perfect.
The protagonist of David Thomas's novel Girl is a macho, laddish twenty something bloke who is mistaken for another patient while in hospital and mistakenly given gender reassignment surgery. Though initially horrified, when the news that reversing the procedure is unviable is broken to him he ends up deciding to commit fully to his new identity, and after cosmetic surgery, hormone replacement and therapy adapts to the life as an attractive, well-adjusted young woman. When towards the end of the book he/she is asked whether he was angry at the doctor responsible (she is suing the hospital) the protagonist admits that, given the chance, she would not want to give up her new life and female identity.
An interesting variation occurs in Jack Chalker's Well World series: All new arrivals on the titular Well World are transformed into one of the native species (and frequently Gender Bent as well.) This is usually followed by a Sense Freak and/or Showing Off the New Body when they wake up in their new forms and eventually leads to an epiphany that they now regard their new body as their natural form.
Subverted in Chalker's The Four Lords of the Diamond series. In each of the books, the main character has his brain pattern imprinted on four prisoners, each being sent to a different planet in the Warden Diamond Penal Colony. One of the bodies is that of a female. Fortunately for the protagonist, he is going to a planet that has the strange property of switching the minds of two people when they sleep with each other (in the literal sense). He jumps at the first opportunity to get himself back into a male body, and never looks back —even though this inevitably blows his cover.
As one might suspect from the title, the entire plot of Justin Lieber's Beyond Rejection revolves around getting an involuntary Gender Bender to this point. Unlike other examples this is treated as a potentially deadly situation requiring intensive medical intervention to prevent dysphoria and death.
Variation 2 shows up in Sean McMullan's Eyes of the Calculor: John Glasken's distress at being reincarnated in the beautiful body of young Valesti Disore initially manifests in a lot of psychopathic behavior (such as amputating the hand of a man who dared to pinch her butt) but in the end she claims she finds being a woman (albeit one with a "baleful and malevolent" reputation) "rather liberating."
In Lois McMaster Bujold's A Civil Campaign, Lady Donna Vorrutyer goes offworld for gender reassignment surgery so she can contest her vile cousin's ascension to her late brother's Countship. Lord Dono soon admits that while she primarily did it out of a sense of duty, he'd discovered there were some advantages to being a man (especially in Barrayar's highly sexist society) so even if he lost he would remain a man in order to explore them.
Slightly subverted in The Warlock Of Strathearn. The main character turns himself into a woman because he falls in love with a lesbian. This works out very well for awhile, and he enjoys many aspects of being a woman. Eventually, though, after his lover dies, he begins to experience the not-so-good parts of being a woman, and begins to want to be a man again. However, his powers aren't working anymore, and he has to make a deal with someone to change him back into a man. He turns out to like different qualities of being either gender.
In The Wheel of Time after Balthamel is resurrected in the body of a Borderland woman he comes to accept his new life as a woman. His/her appetite for sex and women is not lessened in the slightest, the gender change does however broaden his interests and provide him a wealth of new assets.
From Discworld: Although he's only crossdressing, not actually a woman, Corporal Nobbs is reluctant to get back into his male uniform/role after he's spent half of the book wandering around Klatch as Beti.
Andrew Jackson Libby, a character from several of Robert A. Heinlein's works, had his gender changed to female when he was resurrected, when it's discovered that he had both male and female sex chromosomes. He changes his name to Elizabeth Andrew Jackson Libby Long, and tells anyone and everyone that he's much happier as a woman.
The Who song "I'm a Boy" subverts this trope; the narrator can't wait to resume his normal sex role.
Xion from Kingdom Hearts is an iffy example. She is physically male or genderless but was treated as female throughout the game. Regardless, she considers herself female even after the reveal.
Xion: Now its time for the puppet to play her part.
Her anatomy is clearly female at the start of the game and clearly male when she fights Roxas.
Subverted in Misfile. Despite her life being much improved in several aspects, Ash is still vehemently trying to go back to being a boy, even if it means that all the good things she achieved in the meantime disappear. Keeping a firm grasp of "his" male identity remains top priority over all else.
Averted in The Order of the Stick. Roy doesn't seem to terribly mind being female for a dozen strips or so (it helps him get perspective on the kind of person Miko Miyazaki is), but he'd much rather have his "Trouser Titan". The fact that he's just as bald female as he is male probably also helps.
The Wotch positively loves this trope, with four jocks-turned-cheerleaders (who later got a spinoff comic), a male teacher turned Asian girl student and an Innocent Bystander-turned-Perky Female Minion, amongst others. There's even a variation where a woman turned centaur decides she prefers that form as well.
Special mention goes to a couple who keeps swapping bodies and gender as a Running Gag. The one person who has expressed an interest in trying the other gender again recreationally is the girl, not the guy.
Played straight in Cheer (the aforementioned spinoff comic of The Wotch) when Jo, the only one of the the transformed cheerleaders who knows she used to be a boy, freely admits that she and her friends were all troubled as boys and are all much happier as girls, though she still cries when she discovers that no one remembers her former male self's Crowning Moment Of Awesome. The other three jocks-turned-cheerleaders have so far averted this trope, since they don't appear to remember the past.
Largely averted in El Goonish Shive despite all of the constant Gender Bending: Elliot has no interest in remaining female for long and considers his gender-bending Power Incontinence distasteful, Justin specifically rejects the idea even though it would make him sexually compatible with the object of his unrequited affection, Ellen accepts it without expressing any preference (though there are hints that the Loss of Identity associated with Opposite SexCloning Blues was a sore point until she got a new set of memories).
It's touching in Vlad/Vladia's case. There's nothing kinky about her accepting the change — for the first time in her whole life normal people aren't terrified by the sight of her, so she's willing to accept any form provided it's human, which her old, male form decidedly was not. And given that her one attempt to use her supposed shapeshifting powers was a painful, near-death experience she's not about to experiment even given the chance.
The current theory is that Elliot will acquire new female forms again and again until he really likes one of them — then again, it was Tedd's idea. Between flying around as a superheroine and ogling Perky Goth form in a mirror, he may have found this already.
Tedd is the only straight example. He likes this form of shapeshifting because his androgynous face becomes an advantage while close enough to Tedd's own form and he likes to feel attractive. Once this problem became moot it was revealed that Body Swap is #37 on his fetish list.
Variation 1 shows up in Sailor Sun, though it seems less like grudging acceptance than flat-out surrender to hear Bay describe it. (Naturally, it's immediately followed by a Snap Back due to amnesia, proving the first law takes precedence.)
Mocked in one strip of Murry Purry Fresh And Furry; the parody TF comic boils down to "Boys are hideous and live bleak, miserable lives; girls (and boys turned girls) are pretty and have perfect lives with no problems".
Played with in The Good Witch: Angel is fond of using magic spells to force these sorts of second law declarations out of her brother as a form of torment. Played straight with Angel herself, though.
Played with a great deal in The Dragon Doctors, since there are a great deal of gender benders in it. It's all over the map, ranging from genuine gender dysphoria to total acceptance and everything in between.
Probably played straight with Julius of The Key To Her Heart, mainly because being female allows him to have a relationship with the girl he loves, who is a lesbian. also played straight with his mom (who took to her mode-locking to female with gusto) but subverted with his dad, who is very much a manly badass-type who does not take well to his gender-changing.
The emperor from Beyond The Veil embraces this trope mere minutes after changing genders. It's implied issues with a new body were never a big concern and she takes her second-in-command as her new lover (having never found a worthy one as a man) before going back to trying to conquer the universe.
In MSF High Keiri sees that people enjoy it after she changes them so that they'll be less likely to change back when the nightly reset button hits.
The main characters in Whateley Academy play this trope across the entire spectrum. It doesn't hurt that for most of them being turned female was a side effect to gaining the superpowers which make them some of the most attractive and powerful people on the planet. (It's also completely and utterly impossible for them to change back, period.) Still, the degree of acceptance tends to be directly contingent upon the degree to which each character was (knowingly or unknowingly) transgender in the first place.
There is a video Geraldine where a young man is turned into a woman against his will in some unexplained way. After a decade of assimilating to the point of dating, becoming a famous model, and becoming the leader of France, the man turns back on his wedding day. He then ends up with his best (girl) friend instead.
In the Paradise setting, humans are randomly, permanently changed into Funny Animals (with some experiencing a gender-change at the same time). A number of stories follow the journey of gender-changed characters as they come to accept and then enjoy their new (usually female) gender. Some stories take this a notch further into Third Law of Gender Bending territory.
In the SCP Foundation, Agent Diogenes has had his/her gender changed so many times by magical artifacts that, in addition to a now very androgynous appearance, said Agent also is comfortable with the new gender identity they took, that identity being none. Diogenes refuses to pick either, state what the biological sex even is at this point and also refuses to alter things like hair or uniform to make a more masculine or feminine impression.
Take A Lemon: Pretty much inevitable once Marsh realizes she'd received the memories of her alternate universe Spear Counterpart instead of an actual Gender Bender.
In the Futurama episode "Neutopia", a sexless alien first takes away everyone's gender, then when asked to restore them gets everyone backwards. The now-male Leela, Amy, and LaBarbara struggle to save the sinking Planet Express while the feminized men have fun being girls and goofing off. When the "guys" force the "girls" to make a swimsuit calendar, they go along with it a lot more happily than the real women did earlier. Despite all this, the men go back to their original sex with zero protests when the opportunity came up (except for Scruffy, who came in late).
In Mary Shelley's Frankenhole Victor gives himself female genitalia but is extremely hesitant when Elizabeth tries to treat him to stereotypically feminine things. It's subverted slightly when he acts traditionally feminine to date Dracula, but that was only so he could screw him over.
This is definitely not Truth in Television. Messing with a person's gender identity in Real Life usually results in dysphoria instead of acceptance. However, since it's still not possible to literally change a person's biological sex (a so-called "sex change" is essentially cosmetic) and genderbending is much less coherent when gender is not equated to biological sex, there are very few Real Life examples to draw from.
Also, a common law is only to give sex changes after 3 psychiatrists' approval. This is ostensibly a failsafe intended to enforce this trope. Given that most people put a little thought into the matter before opting for major surgery on sensitive areas of their bodies and the obstructionist attitude of many psychiatrists, the soundness of the given reason for this requirement is questionable. On the flip side, many other people seem to think changing sex will solve whatever problems exist in their lives, hence the requirement for psych evals.
The vast majority of transgender (and related) individuals who were/are forced or "received treatment" to align them to what society accepts as their actual gender have suffered immeasurably. Prayer, abstinence, various therapies, medication and many other types of treatments to realign an individual whose gender identity does not match their biological gender (by trying to enforce the biological gender over their gender identity) have failed and resulted in a great deal of suffering for the individual. The same goes for individuals whose gender identity's do not fit into the stereotypical binary gender system. Attempting to morph gender identity severely damages an individual.
The David Reimer case is a famous inversion. When doctors botched a circumcision and cut off the baby's penis instead, some quack psychologist thought he would use this opportunity to prove that gender is based on nurture rather than nature, and had the parents raise this child as a girl instead hoping he would just accept his new gender. This did not work, as the child always felt confused and grew to intensely hate the psychologist who was using "her" as his personal guinea pig the whole time.
Two rare conditions (5ARD or 17BHDD) can cause chromosomal males to develop around puberty rather than before birth. Some people with these conditions come to identify with their "new" gender.