Atton started hitting on me from the first moment of the game. I'm working on getting as much influence with him as possible.
What I like a lot with the romance options is how the influence system can work in your favor. In KOTOR, if you were hardcore DS and killing everybody and everything left and right, Carth wouldn't say anything about it. He'd just keep hitting on you.
With KOTOR 2, I can manipulate Atton to kill with me, and we can enter a lovely DS romance.