Putting your character in situations which they will thrive/fail in will bring out the traits of your character. Testing their limits, while creating epic scenes is guaranteed to hook your readers as they go into this new realm of your character.

Your shy, awkward character may thrive when attacked by a serial killer or you strong, arrogant character may fail when they're kidnapped. You know that phrase fight or flight, yeah that one. Well the way your character handles a situation, ie whether they deal with it or run away, is very telling of your characters personality.

Characters that change personality/show a new side to their personality in different situations show how talented a writer is and how complex their characters are.