Robert Knepper, Heroes

Robert Knepper has a way with villainous roles.

The actor, whose racist, pedophile Theodore "T-Bag" Bagwell Prison Break fans loved to hate, keeps his evil streak going in the new season of Heroes (premieres Monday, Sept. 21 at 8/7c, NBC). But Knepper hesitates to label his new character an out-and-out baddie.

Fall Preview: Get scoop on all the new and returning shows

"People ask if he's a good guy or a bad guy, and it's more complicated than that," Knepper tells TVGuide.com. "You can't just put him in a little niche there. I love the mystery of it. I didn't even know when we started exactly why he was doing what he did. But he's definitely walking more in the shadowy side of life."

As Samuel, the Keith Richards-esque, earth-moving leader of a band of super-powered circus freaks, Knepper's mission is to bring a cherry-picked group of good guys over to his "family" on the dark side. "Samuel isn't quite sure why he needs all these special powers around him. He just knows he needs them," Knepper says. "It's the whole devil-and-angel sort of thing. We've all got powers; it's just how you use them."

Samuel will definitely cross paths with time-bender Hiro (Masi Oka), power-absorber Peter Petrelli (Milo Ventimiglia) and skull-splitter Sylar (Zachary Quinto). Wait, what's that? Isn't Sylar permanently shape-shifted into Nathan Petrelli (Adrian Pasdar)?

Check out our roundup of the best cliff-hangers from last season

"He's trying to get to the root of the guy," Knepper says. "[Sylar] is one of the characters that is a real prize. If [he] can get Sylar, then it's terrific. He wants the deepest, darkest, animalistic side of Sylar."

Knepper notes that his character has to do a lot more than throw some dirt around to get the heroes' attention. "He's smart enough to know that he can't force somebody to do something against their will, because these are people with amazing powers," Knepper says. "They can wipe out a whole village. So he has to be very careful how he suggests to them that it would be in their best interest to help him out. He's not going to strong-arm them."

His plan of attack is simple: find their weakness and strike a quid-pro-quo bargain. "He finds that one Achilles' heel for each of these characters, what eats away at [them] the most," Knepper says. "He says to them, 'Deep in your heart, you know you need to change, and I'm here to expose it to you. And by exposing it, you're halfway on the path to trying to change it or deal with it.' And his hope is that they'll go, 'Thanks for helping me out; how can I help you?'"

See photos of the entire Heroes cast

But like many of the heroes this season, Samuel is searching for his own redemption — which is not so coincidentally the title of Volume 5. "There's a secret that comes up in those first episodes, where you find that he has his own inner path, something that has been done that he needs to correct for himself in order to keep on living with a good conscience," Knepper says. "He's saying, 'I don't want to walk down that side of the road anymore. I don't want to walk in the ditch; I want to walk right up on the road.'"

Of course, just because his character desires change, that doesn't mean he will actually ever alter his path." I think this guy has a wonderful built-in conflict over whether he's doing this for his family or just doing it for himself," Knepper says. "This guy is very much a dictator, and at moments, he can be very much aware that this is totally self-serving. And like a lot of world leaders and dictators, he surrounds himself with a really good core group of people who are not only yes-men, but who are also very, very smart. Some of them know exactly what his motives are, and some of them don't. So it's fun to watch the character go through these different machinations."

See photos of Knepper throughout his career

And Knepper, who claims he never saw an episode of Heroes before being cast, thinks that that fun leads to a season that could restore the show to its former glory. "I think it's compelling to watch right now," Knepper says. "I know I feel compelled when I go to work, and I'm trying to make each page work. Hopefully, that will translate to people who can't wait to see what's next."

Are you excited to see what Knepper brings to the new season?