Last week’s episode saw the shocking departure of one of The Vampire Diaries‘ original characters. Learn how this development will affect Elena going forward.

ET Online caught up with Nina Dobrev following the death of Elena’s brother Jeremy (Steven R. McQueen), and the actress previews how Elena will deal with what has probably been her most significant loss so far (spoiler alert: not well at all).

“It’s very likely that Elena could go off the deep end now that she doesn’t have the one thing that kept her human,” Dobrev warns. Despite her newfound vampire strength, “she couldn’t protect Jeremy and lost the only family member she had left. She won’t take it lightly. It’s going to destroy her.”

But we shouldn’t expect Elena to accept Jeremy’s death right away, as the promo for tomorrow night’s episode indicates. “She’s looking for any solution she can to bring him back. Elena is basically mentally unstable, going a little crazy and everyone is trying to help,” Dobrev previews. But is Jeremy truly dead, then? While McQueen is slated to appear in the next couple of episodes, Dobrev makes it pretty clear that he’s gone, saying that her co-star was “very bummed” by the development but excited that his character got taken to some new, interesting places this season.

TV Guide, meanwhile, has stated that we’ll know definitively by the end of the next episode, so we’ll have to wait and see! But whether or not McQueen is staying on in some capacity, “Losing Jeremy really, really, really changes Elena,” Dobrev says. “Elena’s mourning period is much different than any I’ve ever seen depicted on TV before. She goes off the deep end and spirals downwards into a black hole of death and sadness and misery.”

In the upcoming weeks, you can therefore expect to see a new side to the demure, mild-mannered character we thought we knew. Dobrev says, “I was very surprised where the episodes take her because it’s almost like she’s a completely different person that you won’t recognize to some degree.”

We’ll leave you with a final, tantalizing teaser from TV Line: “Let’s just say Elena invents a new stage of grief to cope with her brother’s apparent passing, and it’s hot.”

Are you looking forward to seeing this new, darker Elena, who will be left with no ties to humanity? Or are you just sad that Jeremy is gone?

The Vampire Diaries returns tomorrow night at 8/7c on The CW with “Stand By Me.”