Vampire Diaries Vampire Diaries

Vampire Diaries star Ian Somerhalder told us that the show would eventually delve into the Salvatore brothers' sordid past — and they'll soon deliver.

"For someone to [promise a person an eternity of misery], they must have done something really horrible, something to warrant that kind of promise," Somerhalder says. "Those things are fun to find out," he teases.

Get ready for the fun! In the Oct. 15 episode, "Lost Girls," we'll see a Civil War-era Stefan, Damon and Katherine (played by Nina Dobrev, of course), and learn how the brothers' blood feud started. We'll also see why Somerhalder's Damon is happy to be frozen in time as "the eternal stud," while Stefan (Paul Wesley) is more tortured about being a 150-year-old teenager.

See photos from "Lost Girls," the show's Civil War-era flashback episode

"Nina and [costar Katerina Graham, who plays Bonnie] and all the people on the show, we're all sort of the same age," Wesley says. "So it's hard for me when I'm on set, I have to really get to this place where I'm like, 'Wait. I'm like their grandfather.' You know what I mean?"

Jasmine Guy joins Vampire Diaries, but she's no vamp

Here are two clips from Thursday's "You're Undead to Me," which starts to reveal Stefan and Damon's long history with Mystic Falls and introduces us to Bonnie's grandmother (guest star Jasmine Guy), who helps Bonnie begin to understand her special talents.

In the first clip, Elena and Caroline work a charity car wash, where Caroline has an interesting run-in with a spectral Damon, who has been detained by his brother and is sending out help messages via crow. (Warning: ruffled bikini and mispronunciation of "chamois" alert!)

In the second, Elena asks Matt what he thinks of Stefan. "Like, he's a serial killer and keeps a clown suit in his trunk?" Matt jokes. As if on cue, Stefan arrives, and as usual, he's got some explaining to do. But that will have to wait. When a Mystic Falls old-timer appears to recognize Stefan ("you haven't aged a day," he says), Elena is prompted to do some research, which yields a 1950s-era photo of Stefan.

Excited for tonight's Vampire Diaries? Can't wait to see the trio in period garb? Stefan or Damon? Sink your metaphorical teeth into the comments section below.