Tonight's Season 1 finale, titled "Family," will force Charles into a potentially deadly decision. The most important relationship in his life, with his daughter Diana (Shelley Hennig), is crumbling. He's learned that she may not be his biological daughter, and she's discovered the truth about Charles' potential for darkness.

"We're asking all of the characters, but particularly Cassie and Diana, to examine the concept of family and decide if family is defined by blood or by choice," executive producer Andrew Miller tells Zap2it. "By the end of this episode, she'll have to choose. Diana's looking at these 'my two evil dads,' one more evil than the other, one by blood, and one by choice, and she has to make certain decisions."

Charles has to decide whether Diana is his priority, or if he can continue to be driven by selfishness. "Charles has thought Diana was his biological daughter this entire time and is now faced with the idea that she isn't," says Miller. "He seems to want to be a real father. In the finale, he'll have to decide what being a real father means and how far he's willing to go for his daughter."

As is appropriate for an episode titled "Family," we'll welcome Stepfanie Kramer back to Chance Harbor as Kate, Charles' mother, who definitely has her own agenda. "Everyone needs to turn to their mom every once in a while, and this is the episode where Charles desperately needs to. Kate will put who Diana is into a very clear perspective for him."

Throughout the season, Charles and Dawn have often been ruthless in their quest to regain the power they were stripped of 16 years ago. When they finally get their power back in tonight's final episode, it's not exactly all it was cracked up to be.

"They didn't really want their powers for any good reasons," says Miller. "They'd talk about saving their kids and protecting their kids, but the reality is that's bulls***." They haven't been protecting their children at all -- hello, witch hunters and demons and zombie-witches and ghosts -- and now, they'll have to be held accountable for their failings as parents.

tsc-secret-circle-diana-cassie.jpg"Magic is a very easy way out, an easy way to feel powerful, but I don't think it makes you a powerful person. In this episode, Charles in particular, because he's done so many bad things, will have to decide how much strength he has as a man," Miller tells us. "He'll have to decide what he's willing to risk for the people he loves. He'll have to redefine himself in a way that we'll recognize from that first pilot episode. He's going to have to play the damn price. Everything needs a consequence for balance. Charles is due."

We're thrilled to see Harold show off those acting chops that have been subdued all season, and we're also excited to see how everything that goes down in the finale impacts Diana. Miller explains that she and her newfound sister go through a bit of a role-reversal as the season comes to its dramatic close.

"When we meet Cassie for the first time, she has nothing but Grandma Jane, who she barely knows. Her mother's dead, her father's dead as far as she knows, she's moving into a strange town with a strange old-by-CW-standards lady," he chuckles. "Diana, by comparison, had everything -- a dad, friends, a great guy. By the end of this season she'll have none of it. She's lost Adam, she's lost to some degree her father, and finding out about her father and Amelia plays into the choice she makes about family that puts her into a very interesting place for next season."

Oh, and in case you were wondering -- yes, there will be a significant death in the season finale, which will force the kids to examine whether they truly are stronger as a circle or as separate witches with individual powers.

The CW has yet to make an announcement as to whether or not Season 2 will actually happen -- so make sure to show your support and tune in to watch "The Secret Circle" live tonight at 9 p.m. EST. If you really want to throw your weight behind the show, check in on it again tomorrow by downloading the episode on iTunes or live-streaming from the official CW app.