Living with the Villain

""Roses are red, violets are blue, your arch enemy goes to school with you.""

- Spud, American Dragon: Jake Long, "Ski Trip"

The hero has a Secret Identity, and so does the villain. On the days that they're not battling, they live or work uncomfortably close to one another - or at least it would be uncomfortable if they only knew who that guy across the room really was. But each one simply doesn't recognize the other one when the costumes are off (as if the voice wouldn't give it away in seconds). Often, they're even best friends or even dating in their uncostumed lives while fighting tooth and nail when in a cowl. Sometimes one of them is aware of it, but chooses not to do anything whether due to manipulation, confidence, or not wanting to touch off a simmering powder keg.

They don't always live together; heroes and villains may work for the same company or go to the same school.

The Reveal tends to be... messy.

Compare Enforced Cold War, where the two sides know that each is the enemy, but are forced to co-exist anyway; and Go-Karting with Bowser, where the two sides know that each is the enemy and are friends in spite of it. Cain and Abel and Dating Catwoman can be subsets of this.

Anime and Manga

 * In the Pretty Sammy series, a Tenchi Muyo! spinoff, Pretty Sammy and her enemy Pixy Misa are actually Sasami and her best friend Misao. This is more excusable than most examples, because Pixy Misa has an entirely different personality than the shy Misao, and Misao herself is unaware of her other self until nearly the end of the series.
 * The villains Ali and En from the "Makaiju" arc of Sailor Moon were disguised as schoolmates of most of the Senshi. The same applied with Chibi-usa's friend Hotaru (possessed by Mistress 9, The Dragon to that series Big Bad) in the third season, and the Witches Five, who worked at Michiru and Haruka's Elaborate University High. In Ami's introduction episode, Luna suspects this of her, but learns she's actually another Sailor Senshi instead.
 * Played with in Digimon Adventure 02: the heroes don't figure out that Ken is the Digimon Emperor right away, but Ken knows exactly who they are. And instead of going to school together, it's more that they know him from being a child star, and at one point, Ken and Davis' soccer teams square off in a match. Davis' team is doing decently well until Ken shows up and owns them.
 * One of the central tropes in Dokkoida?! is that the heroes' and villains' Secret Identities all live in the same apartment and don't recognize one another.
 * Same thing essentially in Excel Saga. The apartments surrounding ACROSS agents Excel and Hyatt house members of the city government task force investigating ACROSS activities. Neither side knows they are living next door to their enemies until they move out.
 * In Catgirl Nuku Nuku Flash, an Alternate Continuity of All Purpose Cultural Cat Girl Nuku Nuku, one of the villainesses of an organization that wanted to control the world was the mother of the young boy ward of Nuku Nuku. At home, she was a very loving, very caring mom who juggled her time between work and her family. At work, she was a cackling scenery chewer sending out the Monster of the Week.
 * To quote Magical Girl Lyrical Nanoha, "Wouldn't it be funny if the master of the Book of Darkness was someone my age?" Yeah, and it'd be even funnier if you had a mutual friend and visited each other. Nanoha gets a message from Suzuka introducing her to Hayate immediately after saying that.
 * In the first A's sound stage, Nanoha and Fate almost meet Hayate and the Wolkenritter at a bath (Arisa meets Vita at one point but doesn't know who she is), and Suzuka considers introducing the two groups, but decides to wait until later. Shamal gets quite a shock in Episode 8 after learning that Nanoha and Fate are friends with Suzuka, who's friends with Hayate, and is thus forced to take precautions to make sure that they don't find out about Hayate being master of the book of Darkness.
 * In Jubei-chan 2 Freesia wormed her way into being adopted into Jiyu's family and was literally living in their house.
 * In Code Geass, Lelouch Lamperouge leads a rebellion in Japan against the occupying Brittanians, while his childhood friend Suzaku fights for them in a powerful mecha. Both are unaware of the other's secret life- Lelouch even wants to betroth Suzaku to his little sister at one point.
 * Code Geass also has Kallen, Lelouch's best mecha pilot, unaware of either of their identities for some time. Then in R2 Lelouch has a sensei and a little brother both working for the Britannians.
 * However Lelouch knew Kallen's secret from day one and did not actually befriend her until after he found out that she was a terrorist
 * Then in R2, two Knights of the round joins Ashford Academy. In this show, half of the important characters of the world war joined Ashford Student Council at some point.
 * In Nightmare of Nunnally, Nunnally's best friend, Alice, is one of the Irregulars as a Number who has received Geass abilities from CC's cells, and her mission is to capture or kill Nunnally as pilot of the Mark Nemo (but Alice doesn't know it's Nunnally).
 * In Mahou Sensei Negima, child teacher Negi Springfield finds himself at various times fighting against several of his students. This causes him great consecernation, because he feels that it is his duty as a teacher to help rather than harm his students.
 * D.N.Angel has protaganist Daisuke Niwa, who has a Super-Powered Alter Ego as Phantom Thief Dark. He finds himself in conflict with classmate Satoshi, a teenage prodigy police commander who is tasked with the job of capturing Phantom Thief Dark, and whose family has been enemies of the Niwa family for generations. Despite this rivaly, Daisuke considers Satoshi his friend, however he also has to deal with Krad, who is Satoshi's Super-Powered Evil Side.
 * Crescent Moon is about protagansit Mahiru Shiraishi, who is helping a band of supernatural creatures called the Lunar Race. One of her classmates turns out to be a member of an order dedicated to hunting down and destroying the Lunar Race.
 * In Nabari no Ou, protaganist Miharu Rokujou finds himself attacked by a subsititue teacher, who turns out to be a member of a ninja clan that wants to abduct him.
 * In the anime Nurse Witch Komugi, the secret identity of the main villain is the heroine's possessed best friend. This is revealed in the opening sequence.
 * In the manga and anime Death Note, Light Yagami does this twice. The first is part of the basic set-up of the show: his father is one of the police inspectors investigating the killings Light is perpetuating. The second
 * Ending up being handcuffed together with L has wonders for their characters.
 * Mobile Suit Gundam 00 has Billy Katagiri from The Union crushing on a lady named Sumeragi Lee Noriega...who works for Celestial Being. Also,
 * In the anime Prétear the main character's new stepmother's maid turns out to be the Princess of Destruction.
 * As of recent events in Durarara!!, the leaders of the Dollars, the Yellow Scarves and the Saika army are teetering on the edge of war. Just who are the three leaders?
 * Another Living with the Villain scenario occurs when Vorona joins Shizuo as one of Tom's bodyguards in order to pinpoint Shizuo's weaknesses and destroy him. She expected that he wouldn't recognize her—what she didn't expect was that Shizuo was so quiet-mannered and unassuming outside of his Hair-Trigger Temper and Unstoppable Rage that she'd barely be able to recognize him.
 * In Tantei Opera Milky Holmes, the four heroines are attending school, where the four villains are one of their teachers, the Student Council President, a classmate and a janitor. Despite the villains not acting any differently than normal (except for maybe Arsene), they haven't caught on.
 * A pivotal point in Kamikaze Kaitou Jeanne: Junior police girl Miyako does not know that Maron is Kaitou Jeanne, and neither realize that Chiaki is Kaitou Sinbad, despite all living on the same apartment floor.
 * In Star Driver, some of the Glittering Crux members go to the heroes' school. The school nurse is found out, though Takuto doesn't seem to have picked out any of his classmates that he fought against. The masks do this somehow. When  wears one, it's not recognized until it is too late.
 * In Fullmetal Alchemist, it's quite some time before the heroes realize that one of the Homunculi they're desperately trying to defeat is actually.
 * A tragic case appears in Outlaw Star. When child assassin Hanmyo attacks Jim Hawkings' ship, both ships are damaged and land at a nearby planet for repairs. Both Jim and Hanmyo meet, and having never seen each other, don't realize that the other is an enemy. They have a fun time together, and decide to meet again later for a date. The repairs complete, both launch... and Hanmyo is killed, in a hurry to finish her assignment and see Jim again. Jim gets back in time for his date, but Hanmyo never shows up. He never learns of her death, or his part in it.
 * Kaitou Tenshi Twin Angel has the eponymous three magical girls in the same class. Their Mysterious Protector is also in the same class. He knows who they are, but they don't know who he is. Their Evil Counterparts and Black Carrier are their classmates and teacher, and neither side is aware of who the other is. Even though their costumes should give it away.
 * Bakura of Yu-Gi-Oh goes to Yugi's school and is considered a friend by most of Yugi's company. However, his alter ego is revealed to be the Big Bad at the final season.
 * This happens very often in the sequel series, Yu-Gi-Oh GX. Saiou, all enroll at Duel Academy at some point. And then there's Professor Cobra...

Comic Books

 * The comic book mini-series Arch Enemies is a spot-on example of this trope; a superhero and his Arch Enemy supervillain share an apartment as their secret identities. Not only do they completely fail to recognize each other, but each hates their roommate much more than their Arch Enemy.
 * Parodied in the comic strip Gorilla Gorilla, where Gorilla and Lizard are roommates that grow giant, repeat their names twice, and fight each other, having no idea no matter how painfully obvious their "secret" identities get.
 * Spider-Man (Peter Parker) and the Green Goblin have this kind of relationship in the early Spider Man comics, as the Goblin is actually Norman Osborn, the father of Peter's best friend, Harry. The trope then gets subverted after Norman dies, and Harry takes up the Goblin mantle; Peter and Harry soon discovered each other's identities, but Peter couldn't do anything about it without losing his chance to cure Harry's madness. For his part, Harry kept Peter's identity secret just to have a bit of leverage to mind-screw him with.
 * Mary Jane ended up demanding they all sit down and have a nice family dinner, and in the end, she was actually the one who got through to Harry. You can guess what happened next.
 * In fact, there's a common fan joke Peter is plagued with this kind of bad luck, since many of his famous opponents tend to be people he already knows.
 * Recently, Petey moved in with a cop, Vin Gonzales. Which would not be a bad solution... except that Spidey is an unregistered superhero, suspected of being a serial killer, hunted by Venom, Kraven's daughter, Green Goblin... And Parker is unemployed and can't afford the rent. Yeah. Parker luck.
 * In one issue of the Marvel Adventures continuity, Aunt May decides to rent out a free room in the Parker household. Who moves in? Doctor Octopus! What happens next? HE HITS ON AUNT MAY.
 * This is in reference to a story in the 70's in which Dr. Octopus nearly married Aunt May.
 * Nineties Marvel hero Thunderstrike had an enemy called Bloodaxe, whom he was certain was either his ex-wife (and mother of his child) or the ex's new boyfriend. This made for stressful family get-togethers (Bloodaxe was actually his new girlfriend Jackie, which is arguably worse).
 * In a more literal example, one issue had Thunderstrike surprised to recognize his new roommate as his foe Stellaris, the Celestial Slayer, who had sworn revenge on him. Luckily, she'd changed her mind on that. Not bad for a series that only lasted 2 years.

Fan Fiction

 * In MGLN Crisis, whom Fate knows well, is a key figure in her investigation into her origins, . Lindy suspects that she moved close to Fate in order to tell her the truth before she passed away.

Film

 * Inverted in the Made For TV movie Re-Animated, where the lead, the villain, and the lead's Secret Keepers are the only ones who do realize the villain and the lead are literally living together—no matter how obvious the villain's evilness and bumbling murderous intentions become, the rest of the cast either fails to realize it or treats him like a harmless Cloudcuckoolander.
 * This is, of course, the basis of the movie Mr. & Mrs. Smith, wherein both characters put up a front of normal life for each other while they go about their real jobs as spies/assassins working for rival firms—until they're both given assignments that lead to their paths crossing.
 * Prizzi's Honor is also about two professional hit-persons who are married to each other. Eventually they discover that
 * A non-secret-identity version of this trope is the central conceit of the 1940 film The Shop Around the Corner and its 1998 remake You've Got Mail.
 * In Pillow Talk, Doris Day doesn't realize that the nice Texan gentleman she's dating and the swinging cad with whom she shares a phone line are the same guy.

Literature

 * The reverse occurred in the Animorphs book series, where Jake, the leader of the titular resistance force, knowingly spent years under the same roof as one of the enemy, who controlled his older brother Tom.
 * Marco had the same situation with his mother, the host body for Visser One, except that he didn't find out about the Yeerks until after she had already faked her own death.
 * The principal of the school turns out to be infested by the Yeerks. In order to keep up the masquerade, the heroes are forced to keep up the image of good student while at school.
 * In Bigtime, Karma Girl features a narrator who uses this fact as a way to track down and discover the secret identities of superheroes and villains.
 * My Teacher Is an Alien. Hell, the title tells you all you need to know. Susan, Peter and Duncan are forced to face the enemy every single day!
 * Although in the sequels, the titular aliens are revealed to have less-villainous motives.
 * In Pyrates, George discovers, to his horror, that one of his favorite neighbors is the villain. Getting kidnapped by him in the second book makes him and his friends properly paranoid.
 * Dimmesdale lived with Chillingworth in The Scarlet Letter.
 * At one point in Les Miserables, Javert takes an apartment in the same lodging house as Valjean and Cosette are hiding in. Javert suspects his neighbor is Valjean, and Valjean recognizes Javert in time to flee, but briefly, this ensues.

Live Action TV

 * Alias has Sydney and Alison Dorren living togther after Dorren kills Francie. Dorren has undergone a procedure to look exactly like Francie. Syd not only takes quite a while to figure it out, she even reveals she is a spy to "Francie" when she thinks her friends might be in danger.
 * Kamen Rider Decade literally has this, as
 * Dexter often lampshades this, commenting on how all of his co-workers are committed to catching murderers, yet no one (except Doakes) can figure out that he is one.

Music

 * Dare one mention "Pina Colada" by Barry Manilow, in which the singer discovers that his ideal blind date is actually his current girlfriend?

Video Games

 * Persona 3 has two notable examples:
 * First,  turns out to be a Nietzsche Wannabe. To make things even worse,.
 * And then there's, who is even unaware himself that he is.
 * In Persona 4 . In fact, near the end when
 * In Ar Tonelico 2: Melody of Metafalica, when you enter into Comsosphere, you are forced to take part in a play where Croix becomes a man named Kuroaki, Luca stays as Luca, and Cloche becomes Reish with  becoming Miwa after she starts the story. In the story, Miwa is a shy quiet girl that Kuroaki takes interest in, and after the third cosmosphere dive, it is revealed to Kuroaki that Miwa, the girl that he's in love with and that is falling for him is the Big Bad. Miwa even admits that she's fallen for Kuroaki but doesn't know how to stop hating people. At the end of the 5th cosmosphere dive, Kuroaki and Miwa enter an epic final battle while Luca and Reish are out cold. Kuroaki attempts to make Miwa come with him and be a better person. Before this can become completely resolved however,  pulls the plug on the story right there, waking everyone back up to reality without a proper ending to what happened to Kuroaki or Miwa.
 * Tsukihime loves this trope; all of the Far Side route villains either live with Shiki or invade his home often enough that they may as well.
 * This happened in Viewtiful Joe 2. Turns out that and used you in order to get the power  needed to rule the world.

Webcomics

 * In Bob and George, the titular characters lived together back in their own universe (as in, not the Mega Man universe) as they were brothers. George was a Superhero, Bob a Super Villain. Apparently they both got powers from their mom.
 * Man Man rents out the basement of his Man-Mansion to his nemesis Dr. Vivisectus, making it convenient for battles between them.
 * In The Magnificent Milkmaid, the title character fights her own friends turned enemies, Chastity/Prixen and Martina/Sweater Puppy.
 * Same also in Chocolate Milkmaid

Western Animation

 * In American Dragon: Jake Long, not only does Jake go to school with Rose (who is a Huntsgirl who hunts dragons like Jake), he has a crush on her. That is, of course, until they figure out they're sworn enemies at the end of the first season.
 * In the Wolf and Sheepdog cartoons, Ralph Wolf and Sam Sheepdog treat each other as coworkers, literally punching a clock and exchanging "Mornin' Sam," "Mornin' Ralph" before the mayhem ensues.
 * Static Shock had this happen a few times as well - several of Static's enemies were classmates of his who had the residual effects from "the Big Bang" kick in at inopportune moments.
 * In the Danny Phantom series, the title character has a crush on Valerie Gray, a demoralized girl from the popular crowd who has recently taken up ghost hunting. Danny, being a half ghost superhero, ignores his friends' warnings and tries to pursue a relationship with Valerie. She would like to be with Danny - if only that pesky ghost boy weren't around!
 * In Batman Beyond, a few of the villains Terry McGinnis (Batman) faced were students or faculty at his high school. In this case, there isn't the arc-based component: the villain is revealed, and Terry is horrified to see the face of his classmate.
 * The first season Big Bad was Bruce Wayne's business partner at Wayne-Powers Enterprises (not that Bruce liked him or anything).
 * And of course the Hooded Claw, Penelope Pitstop's nemesis, was her guardian Sylvester Sneekley in real life. Yet another indication of the Southern belle's stupidity- he made no attempt to disguise his extremely distinctive voice and that nose of his was always visible.
 * In the animated series X-Men: Evolution, the Xavier students have to spend time at a public school as well... which happens to also have the Brotherhood of Mutants as students and Mystique as the headmistress in disguise.
 * Note that they are aware of the Brotherhood from the beginning, although they don't learn about Mystique until a few episodes in.
 * In Codename: Kids Next Door, Numbuh Five lives with her somewhat evil big sister, who is part of the Teenage Conspiracy. The KND's Head of Decommissioning lives with Mr. Boss, who is her dad (he hates all kids but his own).
 * Iron Man: Armored Adventures: Throughout most of the first season, Tony (Iron Man) and Gene (The Mandarin) attend school together and work together to find the Makluan rings they're both interested in, both in ignorance of the other's secret identity.
 * Fairly Oddparents has Mr. Crocker, who is obsessed with capturing Timmy's Fairy Godparents.

Real Life

 * During World War II, Leopold Trepper served the Soviet Union, spying on Nazi Germany. Trepper and the chief Gestapo agent sent to catch him lived in the same apartment building, on the same floor, with neither one knowing who the other was for nearly a year.