[@Ekreture]
Yeah that makes sense. The idea I was thinking about was a hit-man/mercenary type character that has the ability to shape shift, but it takes quite a few days for the character to modify their body and copy the appearance of said target. Essentially he'd have targets, and would spend quite a bit of time studying them (psychologically, socially, appearance, mannerisms, etc.) then the process of shifting would be quite intricate (wrapping self in bandages, laying in a tub of ice for days, etc.). 

The character would be a self-aware narcissistic and depressed person which would typically manifest itself in morbid deprecation and a bit of self-loathing. They know they aren't exactly playing by the right kind of rules, and it bothers them, but they are also vain and numbed to societal expectations. 

Probably more info than was needed, but just the idea I was formulating. Not sure if that fits with your vision or not :P