I was thinking Ron could run into him after he leaves Harry and Hermione in the woods. If I recall correctly (been a while since I read or watched DH), he was staying at an inn and he came across a group of snatchers before returning to his friends? Maybe Draco could have been sent to look things over and that's where he sees him. My take on things was that as Lucius fell out of favor with Voldemort, Draco was sort of forced to take over as head of the family whether he liked it or not. Outside, he acclimates to his role quite well, but inside it really wears him down and by the end, he just wants the war to be over and doesn't care who wins, despite thinking his blood is still superior. 

I play Draco a little darker than the books make him out to be. Less of an all talk coward and more ruthless and calculating. He's willing to go the distance in order to impress someone important, but he'd also turn on them when the time is right. I like to take his posh upbringing to another level as well, taking from that sort of untouchable. old money, yuppie vibe he gives off. Definitely less of a bully now that's he's older as well, and deeper now that's going to see the way that war tears everything apart. I think now that he's got these feelings for Ron (which he finds absolutely disgusting), he'll finally be concerned for someone other than himself and his mother.

Personally, I don't really see Draco convincing Ron to come to the dark side. If he tried, I would picture Draco getting really angry with him, so probably a bit of role reversal there. He might end up being true neutral by the time everything is said and done.

Thoughts? :3