Even psychopaths have fears.
I got to admit, I like Trevor more than Michael right now...but thats not saying much because hes still a gibbering madman, even if he is a madman with some degree of morality.
One example, thats not really a spoiler that I liked, is how if you hang out with Jimmy, Trevor doesn't let him go drinking or go to strip clubs. Its tennis or darts, because he is his uncle and hes looking out for him.
Little touches like that actually go a long way to flesh out the psyche of the character. That is the mark of good character writing at least, something Rockstar is good at in this game, at least
Liking the characters is another story...but hey.