Sam and Ruby try to kill Lilith; Zachariah and Castiel tell Dean he must play his part in stopping Lucifer.
From SpoilerTV
Not really anything new but.... ;-)
So I hear your Supernatural character is going to be involved in a little demon-blood rehab with Sam [Jared Padalecki] and Dean [Dean Winchester].
Beaver: Yeah. Yeah. Dean and Bobby are gonna do their best to, shall we say, unhook Sam [laughs]. How well we pull that off, well, that remains to be seen.
I was told that Bobby actually wants to let him out to fight ...
Beaver: Um, well ...
I don't know how much you can say...
Beaver: [laughs] Well, there's also how much I can remember! You know, let's put it this way. There's a big argument about that, between Dean and Bobby. And each of us kind of shifts in our perspective about what ought to be done. So that's probably incredibly vague. But I'm trying not to violate any secrets, and at the same time I'm trying to remember [laughs].
Well, I know your character is part of a pretty big story arc at the end of the season. ... What do you remember about that?
Beaver: Well, you know, it's not exactly what I would call a Bobby story arc. Bobby is very much a part of what's going on in the last couple or three episodes of the season. But the story arc is really Sam and Dean's response to what's going on with Sam. And Bobby's just part of it. Just part of that. I wouldn't want to overemphasize the focus that's on Bobby. But he's very much a part of the action in these last two or three episodes. ...
From Scifi wire interview.