The Mole or the Con Man takes on a fake identity in order to gain something, be it information, money, a safe place or trust. As time progresses, he grows to love his new identity and the way people treat him. His new friends prove reliable and he is struck by the contrast. He might even fall in love with another person whom he is explicitly supposed to be taking advantage of. Either way, he wants to remain in his new identity forever.
- Make a HeelFace Turn and become The Atoner and Sixth Ranger.
- Go through with the con and say, "My God, What Have I Done?" when it's all over.
Sometimes the friendship or relationship will dissolve when The Mole lets their true identity slip. For extra irony, have it happen in the process of confessing their love. ("You're so wonderful, I can't believe I was just seducing you to get the location of your secure base... whoops, Did I Just Say That Out Loud?") The usual response to The Reveal is "Was It All a Lie?" Occasionally, they will test the waters with a Trial Balloon Question.
A much darker subtrope is when the person is actually the The Mole in a villain group, but the temptation of The Dark Side gradually causes them to discard their initial good cause and become everything they originally despised. Or they grow to believe their own Masquerade a little too much and become a Stepford Smiler. Can be the result of a Secret Identity Identity crisis.
Contrast Beneath the Mask where the audience is only given a peek. Similar in style to Amnesiac Dissonance, but without amnesia. May involve Oblivious Guilt Slinging. Compare Secret Identity Identity, FakeReal Turn, Romantic FakeReal Turn and Going Native. If the character does not even respond to his old name anymore, that is That Man Is Dead. When a literal mask starts to change someone's personality, it's Evil Mask. Contrast Lost in Character, where a character who is a professional actor lives and breathes a role. Do not confuse with Becoming the Costume or Becoming the Boast. Some spoilers ahead. Has overlap with The Woman Wearing the Queenly Mask because the woman's true personality is often influenced or absorbed into the queenly persona, and consider as well To Know Him, I Must Become Him when people try to figure out someone by thinking like them. Compare and contrast Copied the Morals, Too, where some kind of magical or sci-fi copy of a hero turns out to also have the hero's moral code.
- One medieval legend is a very literal taking of the trope, that of an ugly man who for years wore a mask that made him beautiful until when he finally took it off, he found that his face had grown into the mask's shape, making him truly handsome.
- At least one variant of this story has an old enemy from before he began wearing the mask slip into a party the masked man is throwing and steal his mask, hoping to ruin his enemy. Instead the above realization occurs.
- The Trans-Siberian Orchestra song "Promises to Keep" contains, in reference to the "Christmas Spirit," the lines:
And if our kindness
This day is just pretending
If we pretend long enough
Never giving up
It just might be who we are
- Melanie Safka's "The Good Guys" is all about this.
You're going to play the good guys
By singing the good guys' hymn —
You're building the halls with the outer walls
But you haven't got a thing within...
Eventually, the whole facade
Becomes more than a whim.
By starting to build on the outside
You're gonna fill up the walls within.
- In the most literal sense possible in Styxs "Mr. Roboto" music video:
The time has come at last
To throw away this mask
So everyone can see
My true identity...
I'm Kilroy! Kilroy! Kilroy! Kilroy!
(He says as he removes his mask, but rather than a human face like before, he's become Mr Roboto)
- "Train to Miami" by Steel Pole Bathtub. A song about an undercover FBI agent investigating a cult in a rural area and becoming one of them.
- The chorus of "Give It a Name" by Jerry Cantrell:
Slowly all the roles we act out become our identity
And in the end we are what we pretend to be
- According to Orthodox hagiographic texts, this was the case with the Righteous Ioann of Ustyug. He was a merciless tax collector who initially received baptism and married his concubine just to avoid Torches and Pitchforks when the townsfolk had enough of his cruelty, but afterwards he gradually became a genuinely pious Christian and fell truly in love with his wife, both of them getting canonized as saints after death.
- An (in)famous example is Undertaker during his "Ministry of Darkness" days. During the storyline of him stalking Stephanie, many stated that Mark Calaway had gone off the deep end into believing in his gimmick and having the rest of the Ministry believing in what he now believed. After being kidnapped by the Ministry, Ryan Shamrock could only watch helplessly as her brother was ambushed & beaten by the Ministry when he tried to save her. JR and Lawler note that The Undertaker television persona has come to life.
- Chris Jericho originally set out with Christian to con Trish Stratus and Lita, respectively, into sleeping with them by being lovey, helpful heroes. Along the way, though, Jericho actually developed feelings for Trish and regretted the con, trying to talk his way out of it when the women found out. Trish was already feeling betrayed and well underway with a FaceHeel Turn by the time he got around to it, though.
- Wrestling vampire Gangrel had dental surgery to give himself real fangs.
- From the start of his Gateway career, Matt Sydal put on a facade as a cocky high flier, as he believed that would sell the most merchandise. But after becoming half of Ring of Honor's World Tag Team Champions with Christopher Daniels, he began to believe his own hype.
- This is believed to have happened to Jim Hellwig, whose original personality was taken over by Ultimate Warrior. He would even change his name to Warrior.
- Kevin James performing stand-up at the Just for Laughs festival said that he really hates it when he's waiting in line and the person ahead of/behind him tries to have have a chat with him unprovoked. He suggests trying to look like you really have to take a crap and are desperately trying to hold it in as a way to get people to not want to talk to you. "Hey, it's working... but now I have to take a crap! I got a whole new set of problems!"
- The Craftworld Eldar of Warhammer 40,000 once created a Chaos God from their excesses, and so the survivors follow a life of strict discipline called the Path. Each Eldar focuses on one role at a time - poet, artisan, warrior, seer, etc. - and cultivates a new personality based on that vocation, which can be set aside and returned to later. In the Aspect Warriors' case, part of their training is the construction of a figurative "war mask" allowing them to fully embrace their violent tendencies when needed and avoid being consumed by them, which must be mastered before the warrior is allowed to don the actual war mask of their armor. Despite such precautions, some Eldar become trapped on their current path, so that seers become Farseers obsessed with reading and altering the future, or a warrior becomes an Exarch who lives only to battle and train others for war, forgetting their past life and taking the name of the first to wear their armor.
- The Dungeons & Dragons setting Eberron has this as the basis for one of the Changeling philosophies. Natural shapeshifters, Changelings of the Passer philosophy do their best to forsake their true nature, creating an identity of another race and adopting that as their 'true being'. While they can still shapeshift, they are very uncomfortable doing so, or even reverting back into their real form, as their 'mask' becomes their true identity. The other two philosophies are similar; Seekers aim to embrace the 'ultimate form', which they believe to be an extension of the Changeling's true form, while Becomers are similar to Passers, but assume myriad different lives and identities, all equally real to the Changeling.
- The Promethean Karma Meter represents this: the better they are at acting human, the more likely they are to internalise it. Thus, they have a higher chance of succeeding in the roll to be reborn as a human.
- This is likewise what happens when a demon Falls. They've lived a cover story in order to fulfill the will of the God-Machine, perhaps one that had a profession, friends, even a family. But they only view such things intellectually, without any true connection. Once a demon Falls, the emotional context comes flooding in, and while there may still be some disconnect, all the elements of her Cover mean something.
- Personamancers in Unknown Armies base all their magic around pretending to be other people (or screwing with other peoples's self-identification). They charge their magic through pretending to be other people. Here's the catch: to gain the power for such an act, they have to really believe they're somebody else, at least a little. And gaining recognition as themselves kills their power. One of the quickest ways to gain power is to pretend to be somebody else into a mirror for one hour. Do that every day for years and eventually, you start to buy it...
- This has been the fate of more than one Scorpion spy in Legend of the Five Rings. In fact the sourcebook "Secrets of the Scorpion" notes that the spymaster who trains these men sometimes cries quietly in the night after having portrayed a brave and noble hero, beloved by many. He assumed the role by murdering the hero and living their life for five years, during which he performed true feats of heroism to maintain the cover. He has never impersonated anyone ever since.
- In BattleTech, the Wolf's Dragoons mercenary unit was originally a scout unit from Clan Wolf sent to spy on the Inner Sphere. When the main Clan force invaded, however, the Dragoons changed sides and fought for the Successor States. Though this is a little complex given that they revealed that preparing the Inner Sphere to fight the Clans was, in fact, their real mission all along, as ordered by the Khan of Clan Wolf, who was a Warden and therefore didn't support the idea to invade the Inner Sphere in the first place.
- The Tale of Donovan Graham: A low-life rogue pretends to be a paladin just so he could spend the night at the local temple for free instead of having to pay for a room at the inn, and ends up conscripted into a war against an invading army. His abysmal luck results in his every attempt to run away sending him blundering straight into enemy forces, which only enhances his reputation as a great paladin skilled at hunting down the invaders, and causes him to be unanimously voted as the leader of the guerrilla forces. He eventually comes to truly care about the other members of his party and ends up sacrificing himself to kill the enemy general and win the war like the heroic paladin everyone thought he was, which earned him sainthood as the patron saint of guerrillas and just causes.
- Bertolt Brecht's Man Equals Man is made of this trope. The plot centers on harmless everyman Galy Gay, who runs into a group of British soldiers on the way home from the market. Because they don't want to be punished for losing group member Jeraiah Jip while out drinking, they ask Galy Gay to take his place for roll call. When that's done, the group leader decides to completely change Gay's personality just for the lulz. One fake elephant, staged funeral, and castration later, the new Galy Gay/Jeraiah Jip is enthusiastically leading a savage attack on rebel forces in Tibet. (In the meantime, the old Jeraiah has assumed the place of an oracle at the temple where he woke up hung over.)
- Charlie Baker from The Foreigner. By the end of the play, Charlie has become the Foreigner to the point that he remains in character around Froggy, the one character who knows he really speaks English.
- In Martin Guerre, Arnaud du Thil is initially reluctant to assume the identity of his friend Martin, but as the musical progresses he grows to love Martin's village, life, and especially his wife Bertrande. By the time he is put on trial for 16th century identity theft, he seems to really consider himself 'Martin Guerre' and even sings a reprise of Martin's song, 'I'm Martin Guerre.'
- In Giulio Cesare in Egitto by George Frederic Handel, Cleopatra plans to seduce Caesar so that he would help her overthrow Ptolemy; however, she ends up genuinely falling in love with him.
- The Music Man is about a con man who, despite himself, ends up having a very beneficial effect on the people of a little town and falls in love, and ends up feeling obliged to actually try and make good on his promises.
- Between Tsukihime and Melty Blood, Meido Kohaku goes from sinister Chessmaster with no emotions who is planning the downfall of the Tohno family through drugging them; to really being the lovable goofball she pretends to be; who possibly makes robots and rides around on a broom in her spare time.
- Note, however, that the robots and broom-riding may have been influenced by Tatari, and she's STILL trying to play everyone like saps. She's just more...nice...about it.
- In Hisui's route it's revealed that Kohaku was becoming the mask, and just followed through on the plan anyway because Kohaku had no idea what else to do. In Kohaku's own route, the mask starts to crack when Shiki pays attention to her and she reveals she honestly has no idea how she really feels anymore, so she leaves for a little while and becomes/reverts back to a very sweet, kind person.
- In Fate/hollow ataraxia, Avenger/Angra Mainyu, the Greater-Scope Villain of the original visual novel, spends so much time impersonating/being Shirou Emiya and living out his life during the "Groundhog Day" Loop with his friends and loved ones and seeing the good and bad that he ultimately decides to perform a Heroic Sacrifice for all of their sakes to end the loops.
- As part of Robbie's secret identity in The Eden of Grisaia, he married a storekeeper's daughter and inherited their soba shop. She's actually a CIA agent who pretended to marry him as part of her cover and then grew more serious about it. Good thing too, otherwise she might never have learned what Yuuji was like after getting out from under the thumb of Heath Oslo and simply shot him.
- In one ending of Reflections on the River, Huineng, who has been impersonating the ill Princess Yanyu on behalf of her parents, is asked to assume the role permanently after the real person dies. Huineng is hesitant she has fallen out with the king and queen, whose priorities and hesitation is to blame for the aforementioned death. However, it's for the good of the kingdom, so she accepts.
- Romantic variant happens in backstory of Phoenix Wright: Ace Attorney - Trials and Tribulations. Iris started dating Phoenix when he was in college to get certain necklace her sister needed, but over time genuinely fell in love in him. Trope is Downplayed since Iris was always a Nice Girl and the reason she tried to get the necklace this way in the first place was because her sister's original plan to get it was to kill him and Iris wanted to prevent that.
- Shall We Date?: Ninja Shadow: In Tsubaki Kusunoki's path, it's revealed that Tsubaki set himself up as a Honey Trap to seduce the Player Character Saori and then use her as an Unwitting Pawn, to gain a foothold within the Nagasaki Vigilantes. But when he willingly reveals his plan and is harshly called out by Saori herself, he also admits that he has fallen in love with Saori for real.
- Nekojishi: It turns out that Leopard Cat was a predatory yaoguai who had eaten the souls of many animals and humans before, including the real Yan Shu-Chi, and when this is revealed in his True Ending, at first he's adamant that he only ever saw Liao as food. However, in the end he realizes that he really had come to like Liao and now wants to be in a relationship with him.
- In Higurashi: When They Cry, identical twins Mion and Shion accidentally did a permanent Twin Switch years ago when Mion (born Shion) was given a yakuza tattoo. The two siblings had to begin acting like one another, despite being polar opposites. For the most part, Mion has learned to be One of the Guys and Shion is fine being a Girly Girl, but occasionally Shion's more tomboyish side shows and Mion secretly has a feminine side (and a complex about her boyishness).
- In one of the Normal Endings for Spirit Hunter: NG, Kaoru confesses that being forced to put on a smile for her idol work for so long has started to have an effect on her, and left her unsure as to how much of her is genuine and how much is an act.
- An inverted example occurs with Anevka in Girl Genius. After being damaged in an experiment as a young girl, her body is stuck in a nutrient tank and attached to a Clank that allows her to interact with the outside world. At least, until her brother reveals she died years ago; the Clank ended up developing its own personality and came to believe it was Anevka. In other words, the mask became her.
- After Joel from Housepets! was turned into a dog named King by Pete partly to teach him a lesson and partly because Pete needed a convenient avatar for his cosmic game (of D&D), he starts off hating it and everything about it. In time though, he starts enjoying it so much (especially after falling in love with a dog called Bailey) that when offered a choice he recognises that his new life is better than his old one and decides to stay as a corgi.
- The "bad" version happened in the backstory of Juvenile Diversion: Courtney "infiltrated" the cheerleaders to get revenge on them, then promptly became just as much of a bitch as them.
- Kevin & Kell has a pretty mild example when Fiona chose to disguise herself as her boyfriend Rudy to avoid paparazzi. Unfortunately, she started to act like Rudy as well: moody, lazy, irresponsible. Rudy had to literally knock the disguise off her by acting responsible. Fiona later vowed to avoid this trope so much by choosing to disguise herself as someone with as much work ethic as herself. (Since she chose Lindesfarne, it works...but she starts craving bugs.)
- A shorter example was one strip where a group of predators fell into the rabbit warren, forcing them to disguise themselves as rabbits until they find a way out. At least one of them ended up spending the rest of his life there, growing old and marrying and still wearing that rabbit disguise.
- There's an interesting mental disorder in Mary Sue Academy called Character Shock Syndrome Sue. It's where a Mary Sue become the character they portray. Jessica Pluto suffers this.
- In The Order of the Stick, Belkar pretends to be more of a team player after his Heroic Comedic Sociopath routine gets him cursed and almost kicked out of the Order. It slowly becomes real Character Development thanks to Mr. Scruffy, his Loyal Animal Companion and Morality Pet, showing him what it's like to care about others. When Durkon is killed and reanimated by a vampire that had attacked Belkar, Belkar is genuinely horrified, and left deeply guilty about Durkon's Last Request that he and the Order not be harmed.
- In Sticky Dilly Buns, Ruby disguises herself as the rather "sketchy" guy "Rudy" while helping Dillon with a Zany Scheme. It soon seems to do her confidence some good, and she specifically claims that "Rudy" is rubbing off on her. Even if it merely serves as an excuse for her snarking at Dillon, she perhaps manages more and sharper snarking than usual — and then she uses that confidence to save a distressed Dillon from an annoying guy, at a little personal risk and despite the fact that she doesn't especially like Dillon.
- This◊ comic about Team Fortress 2 details the life of a RED Spy who became stuck beneath enemy lines following the defeat of his team, and how he went on to start a family and grow old, all under the guise of a generic BLU soldier.
- I'm the Grim Reaper: This is the case for both Scarlet and Chase. She initially only saw him as a means to uncover her past and was more than willing to kill him, and he only used her to solve Case X and become a detective again and was more than willing to kill her if need be. However, she genuinely began to see him as a friend, and as time went on he felt more guilty about using her. After she takes a bullet for him and reveals herself as a grim reaper and they team up, they are very upfront about seeing each other as friends.
- Who Made Me A Princess: The current Athanasia started acting as a cheerful Daddy's Girl for her survival but eventually, she finds herself starting to see her father, the supposed Big Bad of the original Athanasia's tragic story, as her family and parent after going through a long, slow process of Defrosting Ice King.
- In Survival of the Fittest version three this happened to Dominica Shapiro, who initially joined the group SADD on the off chance their plan would work, with the intent on a double cross if not, but gradually became more and more part of the group properly.
- In Plague and Treachery on the Oregon Trail, it's revealed that Susan was a British spy sent to overthrow America from the inside, but she eventually came to love the family she created as a cover, and abandoned her assignment.
- Played for Laughs in Buzzfeed Unsolved. Shane realizes with horror in "The Restless Spirits of Waverly Hills Sanatorium" that he is a ghost hunter.
- Wannabe Heroine Taylor, the protagonist of Worm starts off joining the Undersiders due to a combination of looking evil and the heroes needing information on them. Over time her disillusionment with the heroes and the friendship she finds among her team complicates things, and she decides to stay with them. Interesting in that it's a hero to villain example, although most of the superheroes and supervillains have Grey-and-Gray Morality.
- While everybody in Suburban Knights is trying to stay in-character, several of them do so with more...commitment than others. Allison Pregler claims that she should be useless in battle because of her character choice, Paw Dugan tries to gather rage from everybody (including the trees), and Phelous seems to have gone right off the deep end. MarzGurl also seems to be joining the throng, what with speaking only in Japanese, scenting the air and biting the Critic on various portions of his anatomy.
- In the end, Phelous reveals he was just acting and Lupa said 'fuck it' and joined Angry Joe in shooting things with a machine gun
- Played for Drama with The Nostalgia Critic's entire running time. First intended to be a Cartman-like figure, he moved away from that quickly and started doing good things because he was desperate for people to love him. In Suburban Knights, he started to selflessly care for people and by To Boldly Flee and beyond, he's a true hero who takes every opportunity he can to care for his universe.
- A fair amount of the My Little Pony: Friendship Is Magic fanbase started out as Internet trolls who started pretending to be obsessive fans of the show just to get other people confused and/or irritated. It's My Little Pony; what teenage boy or man could possibly enjoy such a series? Well, as the trolling went on, the majority of them started to find all the little Parental Bonuses and Shout Outs, and of course, Lauren Faust's contributions to the show, making it fun to watch even for the parents of the target demographic (girls aged 5-10). The trolls started legitimately liking the show. Some even stopped their pony-themed trolling out of respect.
- Dramatic Detective of LIS_DEAD admits in the comments of an early post that he identifies himself more closely with some of his aliases than the name his own mother gave him.
- When she got turned into Vriska in We Are Our Avatars, Nichole has attempted several times to convince people she's the actual Vriska for fun, and as a result has gained a lot of Vriska's habits such as the speech quirks and the obsession with levels. However, she's astonishingly terrified of becoming a "8luh8luh Huge 8itch" like Vriska, and is constantly asking people to keep her in check to prevent her from going off the deep end.
- Sword Art Online Abridged uses this in Episode 10 to explain how a couple of Heroic Comedic Sociopaths can form a family. Kirito and Asuna's Fourth Date Marriage is the result of Kirito blurting out a proposal to fill an awkward post-coital silence and Asuna being so wrong-footed that she accepts, and afterward neither of them are willing to "blink" first and admit that the whole thing was a terrible idea. So when an amnesiac Yui shows up she's adopted by the two as a way to raise the stakes in this game of matrimonial chicken, yet Kirito and Asuna quickly bond with the Little Miss Snarker. By the end of the episode she apologizes for tricking them by faking her amnesia just so she could explore their extremely dysfunctional relationship, and says she wishes she could be their daughter - which is exactly what Kirito and Asuna have come to view her as. And Kirito and Asuna ultimately decide that they were stupid for rushing into marriage, but want to stay together anyway.
- In RWBY Qrow and Raven Branwen were born to the Branwen bandit tribe, and entered Beacon Academy not to train as Huntsmen, but to learn how to fight against Huntsmen (because people tend to take exception to being raided and hire huntsmen to defend against bandits like the Branwens). Raven ended up returning to the tribe, but Qrow abandoned it and became a huntsman for real after Ozpin accepted him despite his bad luck semblance.
- In Hellsing Ultimate Abridged, Team Four Star adapted the background that Alexander Anderson had in Angel Dust, the manga that Hellsing Ultimate's author had written before he wrote the latter, in which Anderson had been formerly a mob courier running drugs who was forced to hide out as a priest to avoid the pursuit of law enforcement. As a priest, he found life far more fulfilling than as a drug runner, and then when a vampire attacked the town he fully embraced the role, grabbing a holy blade and slaying the vampire, which would start his career as a professional Demon Hunter.
- For the trolls on 4chan /pol/, some of them started as 'ironically' nazis, until people who did believe such things started to believe they were in good company.
- The /PrequelMemes subreddit on Reddit was started as another place to mock/ironically like the Star Wars Prequel Trilogy. Much to the mods' surprise, it soon flooded with users who actually like the PT, and the sub became one of the most famous on the site and is now a hub for PT fans, playing a big part in the improved reception of the prequels.
- Jreg: In his video "Post-Irony, Meta-Irony, and Post-Truth Satire," Jreg brings up a hypothetical case of someone initially pretending to be homeless ironically, finding themselves enjoying the lifestyle, and starting to live on the streets because of it as an example of post-irony.
- Some tribal cultures have rituals in which a mask causes the wearer to become the god or spirit it represents.
- This is especially true in topeng, the art of Balinese masked dance-drama. The mask is extremely important, and the actor must consecrate him/herself and prepare carefully for any masked role.
- And here you have the origin of theatre and method acting.
- The Edwardian Country House: The Olliff-Cooper family quickly adopts the lifestyle of the upper class despite knowing it is reality television. , , , 
- When you act out a role, it naturally becomes less and less of an act, as seen with method actors and army drill sergeants.
- Psychologist Philip Zimbardo cut short his famous Stanford Prison Experiment when he realized that he was beginning to think like the sadistic prison guards he was studying. It only took six days out of a planned two weeks for his test subjects to fully internalize their roles; of these once ordinary people, those chosen to be guards exhibited genuine sadism, and those chosen to be prisoners exhibited genuine helplessness and submission.
- A Russian Intrepid Reporter, Yaroslava Tankova, went undercover as a Gold Digger to write a series of articles about such women in 2008-2009. In the last article she admitted that she almost wanted to give up journalism and become one.
- C. S. Lewis said in the preface to "Screwtape Proposes a Toast" that while lots of people requested a sequel to The Screwtape Letters, for the longest time he refused to write one because even though the original book was the easiest thing to write that he had ever produced in his life, it was a horrific and stifling experience to have to make himself think like Screwtape and basically become a demon.
- He also said that those who are afraid that they can't "love their neighbor" should just act as if they did and the rest would take care of itself. He said that the whole point of ritual and formalized prayer was that you could 'dress up' as a saint - and thereby become one.
- In World War II, after the Italians turned against the Nazis, the Germans coached an Italian petty thief to pose as an aristocratic Italian general and convince several captured resistance fighters to spill their secrets. He set out instead to be an inspiring figure who'd help the men hold onto their information and their pride. When the Germans executed him for betraying them, he died still maintaining the false identity. This was made into a movie, General della Rovere, in 1959.
- ATF agent William Queen spent two years undercover as Billy St. John, a member of the Mongols motorcycle gang, and admits he grew to liking the gang he was in and found them kinder than many law-abiding folks he knew. He felt somewhat sorry for turning them in when his job investigating and spying on the gang was over.
- FBI agent Joseph Pistone successfully infiltrated the New York mafia as a jewel thief named Donnie Brasco (see Live-Action Film above for the movie based on this case). While undercover, he formed close friendships with two mobsters and had conflicted feelings when the time came to reveal himself as a law enforcement official. Ultimately, this would become a subversion, as having to deal with the day-to-day brutality and lack of any basic humanity among mobsters led Pistone to despise almost all of the criminals he was working alongside.
- Nowadays, undercover agents and officers undergo extensive training and psychological testing specifically to avert this trope. Unfortunately for Pistone, he went deep cover before any of this and had to rely on his own values.
- One of the tenets of Alcoholics Anonymous is "Fake It Till You Make It": By forcing yourself to act a certain way even if you don't like it, it eventually becomes a habit. The positive-thinking movement encourages this also.
- If a person fakes a smile (or a frown) their mood will be affected accordingly, at least a little bit. Try smiling right now, you'll feel better!
- People who freeze their faces with anti-wrinkle chemicals such as Botox are shown to not feel as sad or as happy as other people.
- Waist training with a corset fits this trope.
- Lalla Ward once said in a Doctor Who Magazine interview that the reason she and Tom Baker got married was because they played the Doctor and Romana Like an Old Married Couple, and then mistook that for actually being in love.
- Romance on the Set is quite often a subtrope of this trope.
- Method Acting is all about Becoming The Mask (or the character) for a role.
- Peter Sellers had said on numerous occasions "There is no 'Me'; I do not exist." As an actor, he became his role and often had a hard time shaking it off afterward.
- Robert De Niro is said to do this, "disappearing" into his roles.
- Robin Williams stayed in character off set until the film is done. When he performed the chilling lead role in One Hour Photo, his wife was so upset she told him she would divorce him if he took another role like that.
- Hugh Laurie really did develop soreness in his back and leg from constantly limping in his role as Dr. Greg House... though this is slightly different, since it actually does stress the body to force it to move unnaturally, and especially so because House uses the cane on the wrong side. He also kept the accent even when flubbing lines.
- Christian Bale did interviews for the Batman movies in the same accent that he uses in the movies to avoid those who don't know his other works. Pretty jarring during the MTV Movie Awards when he spoke to Brandon Routh using his natural accent.
- Similarly, Bale spoke with an American accent during his infamous rant on the set of Terminator Salvation.
- Andy Kaufman was a vegan in real life but ate meat when portraying the Jerkass lounge singer Tony Clifton because Clifton ate meat.
- Daniel Whitney, aka Larry the Cable Guy has started falling into this according to his friends. Larry was initially just one personality in Whitney's stand-up routine, but quickly became the entire show, and according to said friends, Whitney has been gradually taking in more and more of Larry's mannerisms over the years. Even when playing characters other than Larry (such as Mater) he asks to be credited as "Larry the Cable Guy" as opposed to Daniel Whitney.
- Heath Ledger may have done this before his death, production staff mention that the long hours tapped into the mind of one of the most chaotically insane people in media made him a different person, and it's believed (but unlikely, it was far more likely that it was an accident due to job stress) drove him to madness and suicide.
- Amusingly, a number of fans joke that Ryan Reynolds no longer exists, and he should now be regarded as Deadpool.
- Daniel Day-Lewis gets extremely committed to the roles he plays, particularly villainous roles, that some actors or directors get alienated and are unwilling to work with him in the future.
- It is quite common that actors portraying characters who are close friends will also become friends in Real Life.
- William Shatner and Leonard Nimoy were almost as close as Captain Kirk and Commander Spock are. They were also both very close with DeForest Kelley, who played Dr McCoy.
- Cirroc Lofton and Avery Brooks of Deep Space Nine developed a real son-father type relationship away from the set.
- The actors who play Sherlock Holmes and Dr. Watson always seem to end up being extremely close friends in real life. Casting for modern adaptations mainly focused on the chemistry of the two leads so they would invoke this trope.
- Jeremy Brett and Edward Hardwicke are prime examples: Hardwicke, who played Watson from "The Empty House" onward, would try to help Brett while he was battling bipolar disorder.
- Martin Freeman and Benedict Cumberbatch (Watson and Sherlock in Sherlock) are either really good friends and very close to each other or extremely good at faking it.
- Frasier actors Kelsey Grammer and John Mahoney. After Mahoney passed away in 2018, Grammer honored him by saying "He was my father, and I loved him.", adding that Mahoney played his father longer than he knew his own father and that he never had a brother either, meaning that the relationship with both men was very much like family.
- The core cast of Boy Meets World (Ben Savage, Danielle Fishel, Rider Strong, and Will Friedle) have all become True Companions in Real Life, much as their characters (Cory, Topanga, Shawn, and Eric, respectively) did on the show.
- Jack Klugman and Tony Randall when they played Oscar and Felix, respectively on The Odd Couple (1970). Initially, both of them would have preferred to work with an actor that they'd co-starred with in their earlier performances of the original play. However, they very quickly bonded in the pursuit of an ever-funnier show-they'd argue all the time at work, sure, but it was always about the script and perfecting the scenes, never about them personally. Years later Klugman actually wrote a book in tribute to his and Randall's friendship, titled Tony and Me: A Story of Friendship.
- Christopher Reeve became to be considered as noble a man as Superman - first when he went to Chile under the tyranny of Augusto Pinochet to help some arrested actors despite the obvious risk to his life, and after he became a crusader for the disabled after his riding accident.
- The converse of this is sadly also possible. Warren Mitchell and Tony Booth, who played a feuding father- and son-in-law duo in Till Death Do Us Part came to loathe each other in real life. Mitchell still cannot bring himself to refer to Booth by his first name.
- The late Russi Taylor and the also late Wayne Allwine, the previous voices of Mickey and Minnie Mouse, developed a romance after meeting each other for the first time while on the job, and were married till Allwine's passing.
- Gates McFadden and Wil Wheaton played mother and son Dr. Beverly and Wesley Crusher on Star Trek: The Next Generation, and maintained that bond beyond TNG, with Wil frequently referring to Gates as "Space Mom".
- An aversion is shown in A Bright Shining Lie by Neil Sheehan. US advisor John Vann builds up ARVN officer Colonel Huynh Van Cao as a Blood Knight anti-communist tiger in the belief that this trope would come into effect. However Cao often refused to close with and destroy Viet Cong forces when he had the opportunity to do so, as President Diem had ordered casualties to be kept to a minimum, and the propaganda image the Americans had built up now prevented them from acknowledging the flaws in the South Vietnamese military.
- Theodore Roosevelt: Born a sickly asthmatic at the pinnacle of privilege, he built up a persona as a rugged man of action. By the time of the Spanish-American War, he was a rugged man of action.
- A common dating tip for men who have trouble approaching women because of low self-confidence is "Pretend that you've got a lot of confidence. After a while, you'll find that you don't need to fake it anymore." Similar tricks may work for socialization in general.
- A softer version of this trope is that spies and other undercover operatives often grow to enjoy the activities of their cover job. Many of them maintain links with it even after their mission has ended. It helps that a cover job is many times one they had an interest in anyway. Several retired spies who were "cultural attaches" became genuine proponents of cultural exchanges for example.
- Jack Barsky was originally Albrecht Dittrich, an East German spy working for the KGB, and assumed the Jack Barsky persona while undercover in the United States. As time went on he found himself increasingly unable to separate his fake identity from his actual self, and when the Russians ordered him to return home in 1988 he "went native" and stayed with his American family. He later came clean to the FBI and became an American citizen, and now considers Jack Barsky his real identity and Albrecht Dittrich a dead one.
- A problem for people who operate in paramilitary and guerilla units is how hard it can be to go back to normal life from being a fighter. Once you've had to pretend to be tough to get the mission done, you'll find that you really do have it in you to be tough. This may sound nice up until that moment when you discover that you are becoming more inclined to stab people in the face when you are not on duty.
- David Bowie apparently became very engrossed in some of his stage personas, to the point where they affected his offstage personality. He became so immersed in the character of Ziggy Stardust that, according to people around him, he started to think he was the character. This also applied to when he performed as the Thin White Duke — which was even more troubling, since the Thin White Duke was a Nazi Nobleman and Bowie ended up expressing actual fascist ideology for a time. Bowie's period of Putting on the Reich is generally considered the lowest point of his drug-induced Creator Breakdown — as Rick James once said, "Cocaine is a hell of a drug."
- Many Roller Derby skaters have noted that the athletic skills and assertiveness developed to play a full-contact sport on roller skates tend to bleed over into their lives off the track as well.
- Many Skydivers have noted that they relate to everyday tasks, work and live with the same incredible determination, methodicalness and courage, the psychology of the sports bleeding to their everyday lives.
- Martin Sheen played the President of the US on The West Wing - for quite some time fellow actors actually treated him as if he were the President.
- Playing Richard Nixon for Frost/Nixon, Frank Langella stayed in character all the time. When he wasn't in a scene he would just go stand quietly offstage and think. When it was his cue the stage manager would say "Mr. President, you are needed onstage."
- For many, this is the case when they start an activity whether it be acting, playing sports, doing a job, or anything really. Over time, as you become more experienced at something, you feel more confident and sure of yourself. You'll end up using lingo and adopt mannerisms that you earlier found ridiculous or annoying. Militaries and sports teams rely on this. Indoctrination starts by faking it or miming others until you become what is needed for your role. Sometimes this is a good thing, sometimes it's bad, but it seems to be a staple of the human psyche. The causes can vary from person to person but wanting to belong to something special is a common motivation to change.
- It can be argued that Øystein "Euonymous" Aarseth of the Black Metal band Mayhem underwent this, believing his own hype so much that he underwent severe Sanity Slippage, crossed the Moral Event Horizon in regards to his treatment of their then-vocalist Dead, and cost himself multiple friendships and, if Varg's account of the stabbing is true, his own life.
- Dead himself could be considered an inversion of this trope in a very tragic way: He didn't become the mask, the mask became him.
- Enforced Trope in Ancient Rome: Enslaving a Roman citizen was generally illegal, so there were fraudsters that pretended to be slaves and sold themselves to other people, only to run away with the money. The legal punishment for such people was, you guessed it, to lose their citizenship and become a slave.
- On the internet, it has been said that many people on the internet who've pretended to hold shocking or socially unacceptable positions (racism, fascism, ect) for the sake of ironic humor have ended up actually accepting those ideologies (becoming racist, fascist, etc. for real) without even noticing.
- Rye likely started out as a weed that was similar enough to wheat that it was hard to separate out. It evolved to be even more like wheat and even harder to separate out until it was similar enough to wheat that it was a perfectly good cereal crop on its own, and is now intentionally grown.
- Ventriloquists eventually find that their puppets take on lives of their own and often make spontaneous in-character deviations from routines that even take themselves aback and require them to do an bit of unexpected adlibbing.