"The Vampire Diaries" 100th episode will be filled with shocking twists, bittersweet reunions and game-changing milestones.

In the episode, which is titled "500 Years of Solitude," we see Katherine on her deathbed, while Delena deals with their breakup and Bonnie continues to serve as the gateway to The Other Side.

A promo preview video begins with the news that although Katherine survived her heart attack, she is hospitalized and may not live to see another day. In the meantime, Jeremy, Damon, Caroline, Elena and Stefan are drinking and reminiscing about the worst things that the 500-year-old doppelganger ever did to them. Most of them recall how she tried to killed them as Caroline reminds them that Katherine actually killed her.

The show's EP, Julie Plec, told Alloy Entertainment that some familiar faces from the past may pop up in the 100th episode, which pays a visit to "nostalgia land."

TV Line also dropped some spoilers, revealing Bonnie's fate. According to executive producer Caroline Dries, "Part of her personality now is that she carries this cross," says the EP. And while she seems to be managing every dead supernatural being passing through her now, those unexpected "visitors" may "become an issue for her," teases Dries. The ex-witch's relationship with Jeremy will face some challenges, too. "No relationship on this show is safe for too long. They're going to hit some speedbumps."

In addition, TV Line hinted that Klaus will be bringing company along with him on his upcoming trip to "The Vampire Diaries." Originals EP Michael Narducci stated that "There are things happening on Vampire Diaries which are pretty huge. Word travels to New Orleans and Klaus - and perhaps even one other of our characters - will be curious about the events that are taking place in Mystic Falls."

The 100th episode of "The Vampire Diaries," "500 Years of Solitude," airs on the CW on Jan. 23, 2014 at 8 p.m. EST.

Check out the preview video below.