Undercover When Alone is what happens when, in order to maintain the surprise for the audience, a character continues a façade of some sort even when there is no one to see him. This frequently occurs when a character is the Mole, and finding out the Mole's identity is a significant part of the plot (or [[RetCon because the writers didn't know yet that he was]] TheMole as they [[WritingByTheSeatOfYourPants hadn't written that far ahead]]).

Can be {{Justified|Trope}} if a character fears being watched at any moment (especially if [[ProperlyParanoid they're right]]). Also, the character may keep up the facade at all times just to stay in practice and reduce the risk of slipping up in front of witnesses. Can't be too prudent, after all. Another possibility is that the false persona is [[BecomingTheMask starting to affect the character's actual personality]].

Note that this doesn't necessarily have to involve the Mole, but can be any situation where a character is hiding something from the rest of the cast. Maybe they simply have a secret, or are planning a birthday party, [[BreadEggsMilkSquick or are a serial killer]]. As long as the audience isn't supposed to know, and they acted like the secret wasn't the case when there was no one to fool but the audience, it counts.

A form of RedHerring and the opposite of {{Foreshadowing}}. Often a sign of a ShockingSwerve. Contrast TraitorShot when Bob reveals himself to the audience immediately after the other character has left the room and RevealingHug where Bob reveals himself even when there are other characters present, as well as ManchurianAgent, where the character does this because they themselves don't realize they are the Mole.

'''NOTE: Since this trope deals with betrayals, this page will contain spoilers.'''


[[folder:Anime & Manga]]
* In ''Manga/{{Naruto}}'', [[BiggerBad Tobi]] puts on the [[ObfuscatingStupidity happy-go-lucky Tobi persona]] even when he's far away from his partner Deidara when he's forced to flee.
* Anthy from ''Anime/RevolutionaryGirlUtena'', full stop. Not only does she fools Utena and the Student Council, but even [[spoiler: Akio himself, whom she has absolutely nothing to hide from]] gets fed up by her constant [[DissonantSerenity façade]] at one point. Every time she is shown alone she act the exact same way, at some point she is in her bed wondering why she's been so tired lately [[spoiler: when she has been acting as Mamiya with Mikage resulting in double "work" for her]] and there was absolutely no-one with her, no Utena nor even Chu-chu.
* Finn from ''Manga/KamikazeKaitouJeanne'' does this. Especially jarring when she gives her monologues about the evil of Access and Sinbad while being TheMole all along.
* In ''Anime/MobileSuitGundamWing'', this begins to happen to Lady Une when her [[FanNickname Saint Une]] [[BitchInSheepsClothing persona]] seeps into her personal time, but is a sign that she is BecomingTheMask.

[[folder:Films -- Animation]]
* That moment in ''Disney/{{Frozen}}'' when Hans smiles like he's quite taken with Anna, right after they first met. On the edge of a deserted market in the water, under a boat, when no-one is watching.

[[folder:Films -- Live-Action]]
* In the Bruce Willis/Halle Berry thriller ''Film/PerfectStranger'', Berry's character is snooping around Willis' apartment looking for evidence of who the killer is (unbeknownst to the audience, it's her). When she finds evidence that seems to indicate that it's Willis' character, she becomes visibly scared. Apparently this is because the ending was changed to make her character the killer, all logic be damned.

* In ''Literature/DragonBones'', Ward kept his ObfuscatingStupidity cover even when alone, or at least did nothing more suspicious than reading books -- the local FriendlyGhost and GeniusLoci, Oreg, who can see ''everything'' that goes on in the castle, was surprised when Ward showed signs of intelligence while talking to him. Justified in that one of Ward's strategies is to keep his face looking stupid, which is easy to do -- apparently, some expressions that look merely neutral on other people's faces look stupid on Ward, due to his brown, cow-like eyes.
* Exceedingly common in ''Literature/{{Goosebumps}}'' books, particularly books where [[TomatoSurprise the main character was a monster all along]].
* Renata Kleber, a.k.a. Marie Sanfon in ''Literature/MurderOnTheLeviathan'' is a master of disguise who doesn't drop the act even in private and even in chapters told from her POV.
* {{Invoked|Trope}} by Littlefinger in ''Literature/ASongOfIceAndFire'', who suggests staying in character at all times, in case someone unexpectedly enters a room.
* In one ''Literature/LordPeterWimsey'' story, Lord Peter goes undercover to infiltrate a criminal gang. He stays in his cover personality even when alone, to ensure he doesn't accidentally slip out of it when he isn't.
* In the Literature/NewJediOrder novel ''Rebel Dream'', two intelligence agents, Voort "Piggy" saBinring and Sharr Latt, both [[BadassCrew Wraiths]], argue about whether Jaina Solo should resort to this. (She's not TheMole, but she's pretending to be ''a goddess'' [[ItMakesSenseInContext because of reasons]]). Piggy believes she can drop the disguise when she's around those she trusts implicitly, whereas Sharr thinks she should keep it up all the time.

[[folder:Live-Action TV]]
* In ''Series/{{Angel}}'', [[AffablyEvil Knox]] acts puzzled when a large sarcophagus gets delivered to his lab. Turns out he not only knew it was coming, he ordered it, for it contained the essence of his god. Given the nature of his employer, this was presumably for the benefit of any surveillance cameras (or more supernatural forms of monitoring) that might be watching him even while alone.
* TheReveal that Boyd was the head of the Rossum Corporation in ''Series/{{Dollhouse}}'' creates several examples of this. In an interesting variation, one example had him stay in character for a Doll in a FlashForward... whose mind he would soon wipe anyway. This is an example of the writers not having decided that he was TheMole yet, which led to internal inconsistencies with the flash forwards.
* In season 2 of ''Series/{{Dexter}}'', Maria Laguerta is scheming to get her superior fired by pretending to be her friend when she's having marital difficulties. However, when a fight between her superior and her fiancé occurs while Laguerta is in the office, Laguerta curses to herself (before she's spotted by them). Given the later reveal that she orchestrated the fights between the two, this was perfectly according to her plan.
* The ''Series/GossipGirl'' finale revealed that Dan Humphrey had been running the gossip blog through the entire series. This means that whenever he reacted to a shocking Gossip Girl blast while alone, he was just reacting to something he himself posted.
* In the first season of ''Series/TwentyFour'', Nina sniffs out a fake FBI agent at the hospital, tries to get his fingerprints but fails, and then takes Teri and Kim out of the hospital to a safehouse. In the finale, Nina is revealed to be a mole working for the bad guys. No-one else noticed the fake FBI agent, so there was no-one for her to impress.
* Invoked and examined in-depth in the final season of ''Series/BurnNotice'', which revolves around Michael's attempt to infiltrate a terrorist organization. The trope is played completely straight, and the voice-over often points out the difficulties of being undercover 24/7 (illustrated as Michael slowly loses touch with his real self and priorities over the course of the season).
* ''Series/MastersOfHorror'': In the episode "Family", a happy couple move in next door to a SerialKiller VillainProtagonist who is later revealed to have murdered their daughter and everything was part of a plot to get revenge on him. However, despite their knowledge of his true nature they seem to take no caution whatsoever, still acting completely blissful and don't discuss their plan even when they're not in his presence.
* ''Series/DoctorWho'': In "[[Recap/DoctorWhoS19E7TimeFlight Time-Flight]]", why the Master maintains his cover as Kalid, including the strange mystical chanting, while alone is anyone's guess.

[[folder:Video Games]]
* One of the {{Player Character}}s in ''VideoGame/HeavyRain'' is so good at concealing said character's real intentions that you cannot guess them even if you ''overhear said character's private thoughts''.
** FridgeBrilliance kicks in once you realize on a second playthrough that most of his thoughts during key story moments can have a double meaning once you know his true identity.

[[folder:Web Comics]]
* ''Webcomic/TheLastDaysOfFoxhound'', a comic starring the QuirkyMiniBossSquad from the first ''VideoGame/MetalGearSolid'', essentially had to do a retcon to turn Ocelot, the series' MagnificentBastard, into this. Early in the comic's run, Ocelot was clueless about [[AncientConspiracy the Patriots]], and while dangerous, was on occasion easily overpowered by his psychic/psycho teammate Mantis. Then ''VideoGame/MetalGearSolid3'' came out during the comic's run and revealed that Ocelot had been working for the Patriots at least since the 1960s. The comic's creator, Chris Doucette, had to change everything into Ocelot pretending that he knew less than he did in order to become TheMole to multiple sides on behalf of the Patriots.
* In ''Webcomic/TheOrderOfTheStick'':
** Under Tarquin, the Linear Guild avoids revealing to the readers that Malack is secretly a vampire until the protagonists find out on their own. {{Discussed|Trope}} by the GenreSavvy Tarquin after TheReveal:
--->'''Tarquin:''' Well, we're standing around talking about it openly, aren't we? If the protagonists didn't know Malack's secret, we'd still be speaking far more circumspectly about his "condition" and such -- despite the fact that everyone in the room already knew.\\
'''Kilkil:''' Oh, you mean like how we're conspicuously avoiding discussing the fact that before we left the city, you--\\
'''Tarquin:''' Now you're getting it!
** The High Priest of Hel maintains the pretense that he is simply Durkon turned into a vampire, rather than [[DemonicPossession a separate character possessing Durkon's vampirized body]] (primarily by copying Durkon's accent) even when no-one can actually hear him. [[http://www.giantitp.com/comics/oots0908.html Panel 5 of this strip, for example]]. Given [[MediumAwareness the nature of the comic]], maintaining his cover to ''the readers'' could be a valid in-universe motivation.

[[folder:Western Animation]]
* Many of the fake ghosts and monsters in ''Franchise/ScoobyDoo'' remain in character when alone, even though it is of no possible advantage for them to do so.
* In an episode of ''WesternAnimation/{{Archer}}'', ISIS is being infiltrated by an enemy agent going by Conway Stern. At one point when he believes himself to be alone, he mutters to himself, "Conway, what have you gotten yourself into?" His last line in the episode was, in fact, him saying that it was not his real name. Then he [[TheBusCameBack came back years later]], and it turns out "Conway" ''[[SubvertedTrope was]]'' [[RealNameAsAnAlias his real name]].
* In ''WesternAnimation/TheSpectacularSpiderMan'', the Green Goblin spends the second-to-last episode cackling to himself and reciting lines from ''Theatre/AMidsummerNightsDream'' (and [[RhymesOnADime rhyming]] even when he isn't). This would make sense if the Goblin was insane, as in most continuities, or [[spoiler:Harry, who is mysteriously absent from his school play at this very moment]], but in the next episode we learn that neither is the case here.
* A Rare heroic (Anti-Heroic?) version occurs in ''WesternAnimation/AvatarTheLastAirbender''. When Iroh and Zuko are hiding as refugees, Iroh comments he can't find any spark rocks to start a fire to make tea. As a Firebender and in the privacy of his own home, this shouldn't be an issue. He still goes to the neighbor and borrows a set, rather than bend the fire. Of course, given that he had suspiciously warm tea at the start of the episode and Zuko berated him for doing such, it could be that Iroh learned his lesson. Turns out, he was ProperlyParanoid as well.