Okay, just 'coz I feel the need to have a post to point back to and say "See! I knew it!" or "OMG, I was a total idiot!" Here's a summary of things I think are going to happen in Season 3. Probably mostly stuff everyone else is already guessing, but like I said, I want a posted record of what I think right now so I can see how wrong I was.
PLEASE NOTE: I don't read spoilers and the spoilers I've run across (*koff*casting*koff*) will not be referred to at all here. If anyone has confirmation or denial of any of this stuff based on any leaked info or spoilers (see sidebar for definition), PLEASE DON'T TELL ME!
Biggish Stuff:
-Dean will be perky and at peace with his deal for a bit, but something will shock him into a more serious mindset early on. Sam will be a pain about the deal until Dean starts to 'take it seriously', and then Sam'll start to get desperate, and then there will be a fight about not breaking the deal because Sam will die. And it will be shouty and hurty and awesome.
-Dean's deal will be more easily broken than it seems, and will be dealt with conclusively almost as an afterthought before the end of the season. However, he won't be happy about it, because...
-...Sam will start to push his "Dark Side" to try and activate the 'controlling demons' power Ava had, succeed horribly well (still kind of hoping for my
lame theory to be valid in a teeny part), and need to be brought back from the dark by the end of the season. Or as a cliffhanger. In any case, Sam will spend a significant number of episodes being relatively evil.
-Dean will have a total knock-down, drag-out fight with Bobby and/or Ellen regarding Sam. Probably Bobby, because I still think Bobby knows things he's not saying.
-As Sam goes evil, a demon or two will show up to taunt Dean about the whole, "We let you have a year so you could see what a dumb-ass maneuver your sacrifice was. See, now Sam's gone evil, it's the end of the world and it's all your fault" thing, to watch Dean break, and after some nice tasty angst, have it backfire on them spectacularly as Dean pounds the crap out of them in some way. *nebulous hand-waving*
-At some point during this season, Dean will need to try to talk the authorities (more than just a local cop) into believing in/helping with/keeping people out of the way of the demons. I think he'll be trying to talk to Hendrickson, and I think Hendrickson will not believe him until his little FBI flunkyboy gets possessed or is revealed to be working with demons or something, just 'coz that guy has 'evil tool' written aaaaall over him.
-Sam would destroy the world to save Dean. But Dean won't let him, to save Sam from himself. Saving the world, that's just a nice side-effect. I guess that's not really a theory, I just wanted to say it :-)
-In the end, the deal or something else may resurface, and Dean will get taken to Hell, but Sam will use the Colt (since it's in the trunk) to go through the gate and get him back, possibly with an army of loyal demons at his back, and still be evil, or by himself after getting past that pesky being evil business.
Other Stuff:
-ASH IS NOT DEAD, but will turn up within the first half of the season, as a (hopefully unwilling) dupe of the demons, and probably die shortly afterwards, depending on Chad Lindberg's schedule.
-Gordon Walker will get out of jail, possibly by turning info over to Hendrickson. He will then try to rally hunters against evil Sammy and get his ass handed to him.
-Hendrickson will be a giant pain in season 3. He will catch Dean, close to when his time is up, only to have Dean's deal be dealt with by Sam, and Dean know that Sam's gone evil enough to control the demons and is running amok while he's trapped in jail with no backup. And then backup will arrive, in the form of Bobby or Ellen or some completely unexpected direction.
-Songs or song titles likely to be used: Night of the Long Knives by AC/DC, just because.
That's about all I've got at the moment. Like I said, theory only, NO SPOILERS PLEASE. This is just for reference, so I can see how wrong I am! :-D