Comic-Con 2012: 'Vampire Diaries' Cast Tease Season 4, Talk Elena's Transformation

Executive producer Kevin Williamson, serving as moderator for the panel, observed that the new season will see a lot of change for Mystic Falls.

"It's a season of changes," Williamson says. "The one person who is having the biggest change is ... Elena." Viewers will remember that at the very end of the season three finale, Elena was turned into a vampire.

For star Nina Dobrev, having Elena go through this pivotal transformation will be challenging.

"It's always been fun to make Elena and Katherine different," she says. "How do you make Elena the vampire version of herself and different from Katherine? That's [going to be a challenge for season four]. I think that'll be defined from her experiences."

"Everything's going to be heightened," Dobrev added.

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Elena's transformation was something that Williamson and fellow EP Julie Plec had in their minds for season two, but after introducing the character of Klaus, the producers opted to wait for the reveal. ("When we introduced Klaus, it wasn't time," Williamson admitted.) According to Dobrev, Plec informed her of the big change "three of four episodes before" the episode shot. "I'm glad it didn't get out," Dobrev says of the final shot. "It was such a great cliffhanger."

Another character who played a big role in last season's closer was Zach Roerig's Matt, whose life was saved with the help of Elena and Stefan (Paul Wesley). Now that he is one of the only remaining humans in Mystic Falls, will season four see him dealing with more guilt?

"I don't know if it's the season of Matt, but I think it's the season of him trying to stay human," says Roerig. "Matt's overwhelmed with guilt right now. Knowing that Elena never wanted [to be a vampire,] perhaps he might offer up [his arm, neck, a part of his body] for her to feed on."

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Here are five more highlights from the Saturday afternoon panel:

Alaric Flashbacks a Possibility: "[Matt Davis] definitely has contractually -- with his other show [the CW's midseason drama Cult] -- permission to appear," Plec says. "It's possible and it's something all of us would like very much."

More Back Story With the Originals: "Esther, we call her the Original witch but who came before her?" Plec asked, who teased that that is a question that will be addressed in the new season.

More Adult Story Lines?: When a fan asked about whether the show would delve deep into more adult story lines for season four, Plec asked; "How much more adult can we get than the shit weve been doing on the CW?"

Matt and Sheriff Forbes?!: "[Matt] is seeking motherly advice, he's yearning for some physical affection. Sheriff Forbes would be really good," Roerig joked (sort of?).

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Vamp Sex 101: It turned into a running gag near the end of the panel, when the question of how Elena's new vampire status would affect her relationship with the Salvatore brothers -- vampire sex! "It'll happen in half a second," Wesley joked. "It could be fun," Dobrev says. "It culd be a lot of fun," Ian Somerhalder echoed. "It's going to be a add an interesting dynamic for the three of them where she's gonig to need help from these two. They're going to learn a lot together in a very short time."