"I don't think it's possible for me to have a soul."
Trying to be a vampire in a world of humans who hate his kind. All he wants is to go to high school, live a life, but he can't, not unless he finds the perfect girl. Even if he doesn't know it, that's the first thing on his mind, though he would never take the choice of someone turning into a vampire or not.
He's a vampire, duh! :)
Turned by his "lover" Kathrine, along with his brother, she "died" and left Damon and Stefan alone to figure out how to survive. Stefan origionaly was the bloodthirsty demon who killed and seemed to have no soul. Over time, Damon left and Stefan stayed to realize his wrongs and become better, where Damon stayed away and fell to nothing but a vampire who longs for blood and didn't care who he hurt as long as he got it.