Celebration is in order for all you “Vampire Diaries” fans out there! Not only is the popular CW show to airing its 100th episode tonight, and returning from its mid-season break, but we (the fans) are also in need of recognition for still breathing after the last 99 episodes. Anyone who has stuck around for the past four seasons knows that that is a tremendous feat.

And if the promos are any indication, the 100th episode promises the same drama, excitement and heartbreak that fans have come to expect.

For starters, Katherine is on her death bed after falling down the stairs at the end of the mid-season finale. Upon taking the cure at the end of last season, her rapid aging became a major plot point and seems to be on its way to fruition. While this seems less than ideal for celebrating 100 episodes of a hit show, let’s be honest, it just wouldn’t be the “Vampire Diaries” we know and love if the life of pivotal character wasn’t hanging in the balance.

It also wouldn’t be the “Vampire Diaries” if past loves didn’t rear their sometimes ugly, but undeniably entertaining, heads. Katherine and Stefan shared a one night stand that led Katherine to believe that all her past wrongdoings in the "Stefan department" could be forgiven. Though Stefan denied any sort of forgiveness, the two shared a moment at the end of the last episode that suggested their story is not over.

Katherine and Stefan are not the only ones rekindling old flames, though. The latest promo revealed the return of a character we all thought we’d lost forever to Tuesday nights on the CW: Klaus Mikaelson. Cue the Klaroline feels! Prior to season 5, Execute Producer Julie Plec confirmed that the drawn out, complicated, and (at times) hopeless romance between Klaus and Caroline was in no way over, despite Klaus returning to New Orleans. And now that Tyler is out of the picture, it’s entirely possible that Klaus is about to make good on his promise to be Caroline’s last love.

Unfortunately, not everyone is sharing the same good fortune when it comes to their love lives. The mid-season finale served up some serious heartbreak in the form of Damon and Elena.

The first half of season 5 revealed that Damon was once the victim of a secret group of humans that performed experiments on vampires, a group that included Wes Maxfield and Elena’s father. Damon’s escape and subsequent actions, like the murder of Aaron’s family, were also discovered. While Elena had forgiven him, Damon told her he could not forgive himself and he didn’t want her to have to defend him anymore.

As I’m sure many of us are hoping, maybe Elena will fight to get him back. However, in a recent interview with E! News, Nina Dobrev said that one of her characters, most likely Elena, undergoes a shocking transformation.

 “It makes a big splash and it has a huge impact on the show and all the characters,” said Dobrev. “It's such a big spoiler you can't even show me in the promos or anything because it gives it away.”

My best guess would be that Elena gets in some sort of face-altering accident, but that doesn’t seem likely since she is a vampire and can heal herself. Maybe Wes will create another cure and Elena will become human again. Maybe since Klaus is back, she’ll get turned into a hybrid.

The cast and producers have remained tight-lipped about this dramatic turn of events, so for now, we are all kept in suspense. Tune in tonight to see all the madness unfold.

Reach Staff Reporter Alex Reed here.