'The Vampire Diaries': Will Bonnie's 'jacked up headspace' bring mayhem to Mystic Falls?

tvd-422-walking-dead-bonnie-bennett-kat-graham.jpgBonnie Bennett ( Kat Graham) has been a mercurial character for "The Vampire Diaries." Early on, the series struggled to figure out how to make the powerful teenage witch a significant part of the action without presenting too many easy solutions for the gang's supernatural problems. Until this season, Bonnie's emotional payoff -- from the deaths of loved ones and other notable traumas -- happened mostly off-screen, due to a large ensemble cast of characters and the series' breakneck speed.

Season 4 is certainly making an effort to make up for all of that. Tonight's episode, "The Walking Dead," pays off a lot of Bonnie's emotional turmoil from the last four seasons. This year, Bonnie's been truly battered by the Mystic Falls madness, culminating in the tragic loss of her ex-boyfriend, Jeremy, and her overwhelming grief and confusion has driven her to make a startling decision: She's teaming up with Katherine.

"Her headspace has been pretty jacked up. She put all her faith and trust in a mentor after a really dark time in her life, and he turned out to be a looney tune, and then she had this ancient immortal who is messing with her head," says executive producer Julie Plec.

Going into this episode, Bonnie thinks she's overcome Silas's psychic grip on her. "She really believes that she's found the strength inside to keep him out of her head, so she thinks that she's got a one-up on him," Plec explains. "She's going to take that opportunity not only to stop him from doing what he's trying to do, which is dropping the veil all over the world, but also to find some way to put him down."

In order to take Silas out, Bonnie has to reach out to her witchy ancestors, which has historically been a dangerous choice for her. Plec says, "Unfortunately, as she says at the top of this episode, 'There's only been one person that's been able to put [Silas] down, two thousand years ago, and that was Qetsiyah, so I need to go ask her for some advice.' What Bonnie does, how she does it, and how it connects to ghosts suddenly walking through Mystic Falls is all part of the next episode."

The ghosts that return aren't all bad -- but they're not all good, either. The Original little bro, Kol, is back and he's out for blood. "Kol is upset. Kol feels like he was a sacrificial lamb in the race to the cure, and he ain't having it. He comes back to have it out with the last remaining living part of the fierce twosome that took his life," Julie says. There will be a brief reunion with one of his siblings, but they don't exactly hold each other and cry. "It's vengeance. There's a moment in which he sort of chides Rebekah for grieving him all of two seconds."

Photo/Video credit: The CW