The Vampire Diaries' Season 5 scoop: Julie Plec talks Stefan's doppelganger drama, Jeremy, and Damon's happiness

"The Vampire Diaries" has done it again.

Going into tonight's Season 4 finale, "Graduation," we knew a few things would happen: The gang would graduate, in a poignant scene that celebrated their history together. Elena would, once again, make a choice between Stefan and Damon. One character who had previously died would return from the dead. And, of course, we knew that someone would take the cure for vampirism and turn into a human. But while we were busy asking who would get the cure and who would spend the summer making out with Elena, we kind of forgot about another season-long mystery: Why won't Silas let anyone see his real face?

The slight of hand gave us one of the most jaw-dropping finale twists ever... and it was just one of many. We spoke with executive producer Julie Plec about what sort of fall-out to expect from some of the most surprising finale reveals when the series returns in Season 5.

1. Silas has a doppelganger -- and it's Stefan. Yes, the Petrova women aren't the only ones with the doppelganger enchantment in their blood. All of the convoluted twists regarding the legend of Silas, his goals, and his abilities came together. Thanks to a loophole, Silas came back to life, revealing that the immortality spell itself had a loophole: doppelgangers. Silas and Stefan share the same face. Stefan is Silas' doppelganger, and now he's trapped in a safe at the bottom of an ocean.

This is a storyline that has been in the works for about a year. "Last year, when Season 3 was over, we kept a small group of writers and we stayed for five weeks, to try to break the broad strokes of Season 4. Last year, right around this time, we came up with the doppelgänger pitch," executive producer Julie Plec tells us.

There were some complications to introducing another doppelgänger character. In Season 2 and early in Season 3, when Nina Dobrev was playing both Katherine and Elena regularly, she grew worn out, physically. Some of the decision-makers behind "The Vampire Diaries" were concerned that playing two characters could take a similar toll on Paul Wesley.

"We had to convince a lot of different people of how it could work and what could make it work," Julie says. "So that we didn't end up in a similar situation as with Katherine and Elena, where we exhausted Nina to the point of being unable to get out of her bed, because we accidentally overworked her so much. Creatively, everybody was very excited about the Silas doppelganger, it was just a matter of how long it took us to cement it, knowing that's fundamentally what we're going to do."

At the moment, Paul's not concerned about working too hard -- he's just excited to face a new challenge on the show. "He is so happy," Julie laughs. "Playing the straight man hero is not always the most exciting job for an actor, and Stefan, of all our heroes, is the straightest on the show. We get to go deeper into his ripper side sometimes, but for Paul, those moments are just pocket moments of opportunity to dig deeply into his craft, and a lot of other times he feels like he's just grooming his hero hair. So obviously, he's very enthusiastic about this, and has been supportive of it all along. He's been dying for something; to be a jerk, to be evil, to be the bad guy, to be able to stretch his muscles."

And in Season 5, he definitely will.

2. The resurrection of Jeremy Gilbert: "Vampire Diaries" fans are used to characters dying -- and occasionally, they pop back up later, whether it's as a vampire or as a ghost. Still, we were (pleasantly!) surprised to learn that Jeremy was coming back from the grave permanently, particularly because his goodbye episode was so heart-wrenching. Didn't the writers worry that resurrecting him would dull the impact of his beautiful, memorable send-off?

"It's something that we talked about a lot," Julie says. "Our intention, originally, was to say goodbye [to Jeremy] permanently. But then a lot of questions came up about the power of this girl losing her only living relative. It was so important to her journey at that moment. The global, eternally reaching tragedy attached to that is really sad, and really depressing."

Though Jeremy had to die in order to push Elena into the next phase of her life as a vampire, the writers quickly realized that it'd be impossible to bring her back from that dark, desperately tragic point in her life unless they revived Jeremy. Without him, Elena was looking down a long, black tunnel of depression -- and that wouldn't make for a particularly lively Season 5.

"We argued a lot, in the writer's room -- could we successfully bring this character back in a way that wouldn't feel cheap? Ultimately, I think that the way that it plays out, it does feel like the natural gift at the end of the season for this character that has been through so much," she explains.

Now Elena has a chance at some happiness in Season 5. "[Getting Jeremy back] resets her, in a way, where she can now get on with her life and live like the Elena that we know," Julie says. She is cautious, because she knows that some viewers might not be pleased with the loophole Jeremy steps through to return to the land of the living. "Critically, you can look at something and go, 'Well, that's a take-back, it's not fair,' but emotionally, I think, it's a positive. We might get hammered for it. We'll see. I'm hoping people will be so glad to see our Elena pull her life back together, they'll accept it."

3. Bonnie will still factor in to the storylines. Jeremy didn't exactly get a free ride back to the land of the living. Bonnie sacrificed herself in order to bring him back for Elena, and now she's trapped beyond the veil -- invisible to everyone, except for Jeremy.

It's certainly a tragic loss, but don't worry, Bonnie fans. Kat Graham will still be a big part of the show. "Here's what I'll say about Bonnie: I haven't personally seen 'Being Human,' but I do know that they have a ghost character that operates pretty successfully on that show," Julie says. "This is not the last we've seen of Bonnie. If anything, she will be right there in the middle of story next season, just with a few new complications."

4. Delena goodness! By giving Jeremy his life back, Bonnie essentially gave Elena her life back, too. Unencumbered by the sire bond, her grief, or a gaping hole where her humanity should be, Elena finally got to evaluate her love life with a clear head -- and she chose to be with Damon. "In death, you're the one that made me feel most alive," Elena told him. Cue the mouth touching! Now, with her vampire boyfriend at her side, she might just be able to enjoy college.

It's been a rough few years for Damon when it comes to his love life -- but Julie tells us it's finally time for him to have some legitimate joy in his life. "Yes. Absolutely," she says. "We're going to get to see Damon trying to be a good boyfriend, and while it's not going to be easy, he's going to try like hell to make it work, and they're going to have a real opportunity for happiness."

5. And what about Katherine? This season, we've seen a much more vulnerable side of Miss Katerina Petrova. She spent most of the year on the run. When she finally opened up and fell for Elijah, he rejected her in favor of a new beginning with his family. And then, in a moment of weakness, she allowed Elena to get the upper hand in a major showdown in the high school hallways. Elena, driven by very human emotions, shoved the cure down Katherine's throat. The thing that Katherine fears most is mortality. Elena gave it to her.

Just don't expect Katherine to go all Elena on us now that she doesn't have to drink blood to stay alive. "As a human, she's still very, very bad," Julie laughs. "If anything, she feels silly for letting herself get vulnerable, and she's taking out that frustration of her own vulnerability on Elena. If Elena goes after her, Katherine's still ready to kick that puppy."