D is for Dean Winchester
In the grand tradition of tough guys with the last names of gun manufacturers, along came Dean and Sam Winchester when Supernatural debuted in 2005. The brothers team up to fight demons and ghosts and creepy monsters together. Sam is set up as the "good" brother, the one who (at first) is in a stable relationship and has ambitions about the future. Dean is the bad boy, the wisecracking, love-'em-and-leave-'em type. He loves burgers and women and beer. But Dean quickly shows himself to be more than his stereotype.
What intrigues me so much about Dean is the conflict within his nature. His devil-may-care attitude belies a deeply emotional interior with strong ties, holding family above everything. If Dean had to choose between saving the world and saving his brother, he would choose his brother every time. It is Dean who angels call upon to be a force for good, Dean, who doesn't even believe in God. The dichotomy (big word alert!) between good and bad that exists within Dean is what makes him by far my favorite Supernatural character.
And D is also for Damon Salvatore
Damon Salvatore is another bad boy half of a good brother/bad brother pairing on The Vampire Diaries. (I'm a fan of the show, not the books, so I'll be exclusively discussing TV Damon.) Bland brother Stefan immediately captures the heart of human heroine Elena, but it's Damon who insinuates himself into their lives and wreaks such interesting havoc.
I keep coming back to Damon again and again because he has so many layers. Spoilers ahead--be forewarned. Over the course of the show, we learn that it was Stefan, not Damon, who chose the life of a vampire for himself and his brother. Damon was an unwilling participant at first. Damon may have embraced the life with no wish for redemption, but only after accepting the mantle of vampire which was thrust upon him. He doesn't spend his time torturing himself about what he is like Stefan does.
Like Dean, Damon also uses swagger and bravado and wisecracks to cover his inner self, a man that feels so deeply that he is in agony when he does open himself up to his emotions. I already liked Damon, but there was a moment in Season 2 that absolutely sealed it for me. In this episode, Damon loses a woman he had made a real connection with. She is a vampire who is dying from a werewolf bite (shut up--don't judge me--this is high-quality TV), and in the end, Damon kills her, making her death much easier than it would have been if the illness from the bite had run its course. It's agony for him, and when it's over, Damon has an existential crisis: