Hyde Plays Jekyll

Sometimes, Mr. Hyde's not interested in making Dr. Jekyll do anything. He just needs a piece of information that he knows that Dr. Jekyll and all the other good guys have. Unfortunately, all of those good guys know that whatever Hyde's going to do with that information, it's not going to be good for them. What's a poor Superpowered Evil Side to do? Well, if he just claims to be his Helpless Good Side, he might be able to trick them, right? After all, it's not like they look any different from each other. This is when one part of a Split Personality intentionally tries to pretend to be the other half. Note that the two characters must be within one body in order for this trope to apply. Otherwise, it's Spot the Impostor or Twin Switch. In a way, this is perhaps the ultimate form of Spot the Impostor, since there aren't even two bodies to let the others know that there definitely is, in fact, an imposter. Just two minds, and if one mind has the other's mannerisms down pat, it can be very difficult for others to figure it out. The best way to beat it tends to be by Fighting from the Inside or noticing Something Only They Would Say or an Out-of-Character Alert. Notwithstanding the description above, any personality might do this. The Superpowered Evil Side might try this in order to get the good guys to let their guard down and let him get at the Applied Phlebotinum. A Helpless Good Side might do it in order to bluff some bad guys he'd otherwise have to fight. There can be many reasons. See also Impersonating the Evil Twin and Mask of Sanity.