Well...my current character, I've only been playing for about 6 sessions so it's way too early to understand him completely.
But. He's a Chaotic Good, I'm trying to role-play him as a Shonen protagonist. This far it's only gotten him beaten up and taken advantage of XD
He's very naive, and believes the reason he should fight is to grow strong enough to protect anyone. Problem is...hes not all that smart, and even less charismatic.
And far too aggressive for his own good, he's almost more agressive than my last character which was...well...hard to top.
I like to take my time playing my characters, so I almost never have full backstories going in, and often throughout the campaign, their alignments will change as they evolve due to their surroundings and events that happen to them.