From what I know of the Ultimate version of Venom the symbiote's really just a suit that was designed to cure cancer. It's not much with the brains itself but that's not really the point. The thing about it that really kinda bites is that there's a major plot·hole involved with it.
See, Pete wears it for a time and then breaks free of it...after which he destroyed the thing. Eddie Brock had the good sense to make more than one version of the suit and after he figured Pete's whole power trip with it he figured he'd give it a shot himself. Now, the problem with this is that the suit started making moves and decisions, overriding Brock for the most part, as though it had the memories from it's being connected to Pete...
...only this suit was never attached to Pete. That was a different suit that had been destroyed. You read all the little boxes and character thoughts and it's all pointing to the suit knowing the whole of Pete's deal from his having worn it...which he didn't.
I like to think the guy's at Marvel aren't this dumb. Then again, they could've had a kegger in the office that day.
So, what's the deal with this mess?