Tim Kring's spoilers for season 4:
Claire Bennet: Everyone’s favorite cheerleader will (one presumes) leave her cheerleading days behind to pursue higher education at a Washington D.C. college. Side plots that get in the way of Claire’s education include HRG and Sandra’s ongoing divorce, and a mysterious suicide on campus that draws her in. Update: Claire will also get a quirky roommate in Madeline Zima.
Peter Petrelli: Peter has gone back to his life as a paramedic, and has essentially cut himself off from the rest of the Heroes. His isolation ends when he falls for a woman described as “fascinating” and “powerful”. Powerful is actually put in quotes, so I’m assuming she’s either superpowered or “powerful” as in wealthy.
Nathan Petrelli: Still discovering new things about himself, mostly because, well, he’s actually Sylar, and not really Nathan.
Matt Parkman: After wiping Sylar’s mind and convincing him that he’s actually Nathan, Matt will have a hard time living with himself. This makes living with his wife and son “impossible”, so I don’t foresee a very happy family life for ol Matt, though I don’t see why. Why is he so bothered about wiping the memory of a notorious, dangerous serial killer? I guess he’s a better human being than I.
The New Company: Get this: Angela Petrelli and HRG forming a new, kinder version of the Company is expected, but they’re joined by … Tracy Strauss? Yup, that seems to be the case. Building 26 serial killer Tracy Strauss will be joining this new Company, just in time to confront another organization out there who is also recruiting Heroes. This new organization’s recruiting process is being described as “fascinating, dangerous and potentially deadly”. Looks like we’ve found our new villains. Or have we? Update: But we do know one thing: Robert Knepper will be playing one of the new bad guys.
Curiously, no news on what Ando, Hiro, and Mohinder will be up to…