'''Basic Trope''': The SplitPersonality is an antagonist.
* '''Straight''': Bob, the shy and kind protagonist, develops a split personality, Evil Bob , who is rude and offensive, and causes problems for all his friends.
** Bob is a saint. Evil Bob is a supervillain planning to TakeOverTheWorld, and doesn't care how many [[KickTheDog dogs he has to kick]] or [[EatsBabies babies he has to eat]] to do it.
** Bob is altruistic to the point that he'd sacrifice his life to save even a wicked person. Evil Bob is a terrifyingly amoral HumanoidAbomination, dead set on exterminating reality.
** Bob is loving and kind. Evil Bob is angry and lashes out at people from time to time.
** Bob's "Evil Side" is just his negative characteristics (anger, pride, etc.) and he has to suppress them.
* '''Justified''': A traumatic event triggered a rage inside Bob that is battling for control.
** Alice is a villain who develops an heroic split personality.
** [[IronicName Evil]] [[DeathbringerTheAdorable Bob]] is a mentor personality who guides Bob to do the right thing to do.
** A traumatic event triggers a split personality inside Bob. This new personality was created to help Bob get through his problems.
** Bob is a StepfordSmiler and his "split personality" is really Bob when his facade breaks.
* '''Double Subverted''': That was a ruse. The new personality is manipulating Bob and giving him bad advice.
* '''Parodied''': Bob has a demon in fetus form literally inside his brain.
* '''Zig Zagged''': Bob has four personalities; Evil Bob, who loves to rape children; Mark, a StrawLoser who bluffs to burn people down that used to be Bob's original personality before he had a traumatic incident; Tom, a StepfordSmiler BrokenAce that he developed as a defence mechanism; and Tim, a FriendToAllLivingThings who is a moral compass to Bob.
** Bob only has one personality.
** His other personality is exactly the same.
* '''Enforced''': "How can I add angst to [[MessianicArchetype Bob]], the saint [[AngstWhatAngst who might just well have achieved nirvana?]] Give him an evil personality trying to take over!"
* '''Lampshaded''': "Bob, I will give you an advice. Your worst enemy is yourself."
* '''Invoked''': [[EldritchAbomination Ksogrians]] [[MindRape inflict psychological trauma to Bob]] [[BeingTorturedMakesYouEvil so that he would help their plan to destroy the world instead of fighting against them as the prophecy told.]]
* '''Exploited''': Emperor Evulz uses Bob's evil split personality so that he can brainwash him into a mindless killing machine.
* '''Defied''': Bob seeks professional help, and with the right combination of drugs and therapy, Bob manages to take control of his demons.
* '''Discussed''': ???
* '''Conversed''': ???
* '''Deconstructed''': Bob's evil side comes out at all the worst times, breaking most friendships before they have a chance to start. As a result, Bob finds himself alone all the time, depressing him more and making it harder for him to resist his evil side, until he eventually stops bothering with resistance and [[ThenLetMeBeEvil just lets his other half do its thing.]]
* '''Reconstructed''': ...Until he meets [[AllLovingHero Alice]], who brings out the good in him and becomes a functional MoralityPet. Evil Bob tries to send her away like the others, but after the first attempt, Bob realizes he can't leave things the way they are and sets about finding a way to bring it under control again. He and Alice eventually become TrueCompanions ([[OfficialCouple if not more]]), and Bob finally has a means of fighting back against his dark side.
Back to EnemyWithin
%% Optional items, added after Conversed, at your discretion:
%%* '''Implied''': ???
%%* '''Plotted A Good Waste''': ???
%%* '''Played For Laughs''': ???
%%* '''Played For Drama''': ???