another way to reveal a character is through subtext. one example i read which always stuck with me is from 'as good as it gets,' when a woman is about to walk her dog and jack's character steps into the hallway, the woman goes back inside to avoid having to deal with him.
another way is through archetypes used as a basis to be expounded upon. to a lesser extent, even a stereotype gives the audience a jump start on the character. (caveat: having just watched stephen king's 'the mist,' i cringed at the stereotypes. but, that's king, master of the stereotype, more strikingly in his side characters.) stereotypes are important tools if used well, imo. i say this because a lot of characters start off as stereotypes.
for example, a young hotshot lawyer invited to join a big-time firm. from tom cruise to kanoe reeves, they're all about the same in content when they start. until, naturally, the story forces them to be torn apart and they have to make choices. the movie 'crash' is accused of having too many stereotypes. the thing i'm plodding along with has a stereotypical cocky flying ace.
then again, what rookie cop isn't the stereotypical guy wanting to clean up the whole city? what top gun isn't an arrogant asshole? for the purposes of telling most stories, what southern baptist preacher isn't a loudmouth fire-and-brimstone belcher?
these don't reveal character as much as instill an instant understanding of them to build on or depart from. for example, invariably the stereotypical inner city punks have more to them than meets the eye (often brought out through, ugh, being taught to dance or sing or math or simply beaten into submission by a hard-ass principal with a bat).
nm talked about the growing cloud. that's a parallel, a symbolic representation of his mood. here's a movie example from the great movie 'the ghost and mrs. muir.' someone carves 'anna muir' (the MC's daughter) into a post by the sea. as mrs. muir ages, the post begins to fall to the side, until, finally, the post is almost ready to be washed away at the beginning of the scene and we know she's going to pass away. that said, once that black cloud dissipates, so too is it likely the character's mood will lighten. i mention this because i'm not convinced these things reveal the character much, per se. they're symbolic, sure, but not necessarily character revealing all the time.
imo, your character has to stick with what's likely given their psychological profile. if they veer from that, that change in course has to be justified. everyone likes to think we're special ~ we ain't. every single one of us fits into a profile. i've had that proved to me and was more than slightly taken aback/amazed. then i saw the book. it's not a short list we all fit in, but it exists, and as far as characters go a few hours isn't usually enough time for a soccer mom to execute fifty people sans a psychotic break. i can be pushed into robbing a bank if i had to, but that's not to say i'd rush in guns blazing, blowing the tellers' heads off. i'd rob that bank in a manner that my psychology dictates... as my psychology dictates the justification for robbing a bank, lol.
i don't think that's necessarily character revealing, either, just food for thought/debate.