By Sandra Gonzalez
Updated January 12, 2012 at 11:26 PM EST
Bob Mahoney/The CW

It seems as though even Vampire Barbie has her dark days. And tonight’s episode of The Vampire Diaries will find poor Caroline having one of her darkest days yet as her 18th birthday approaches. The small issues that has the birthday girl down in the dumps? Vampires don’t have birthdays.

“This is Caroline’s first realization that she will never be normal and there are a lot of things that she will ever be a part of — and one of them is her 18th birthday,” says Candice Accola. “I think a lot of people look forward to their 18th birthday, and I think it’s a year that marks when you’re an adult. And so it kind of is also a realization she will always be a teenager — a young teenager forever.”

Luckily, the gang come together to throw her a party — even though she wants nothing to do with it. “Caroline threw the first party [of the season for Elena’s birthday] and Caroline is a neurotic party planner — it was a big hurrah,” says Accola. “This time around, shes not in the mood to celebrate. This is the first time that the characters are saying ‘Caroline we’ve never seen you like this.’”

Meanwhile, executive producer Julie Plec told EW last night at a TCA event that the episode will also find Caroline none too happy with Tyler’s involvement in the less-than-kind happenings from last week. (Read the recap here.) “She’s not happy about what Tyler did and his part in the whole thing. She is really very upset with him as a person, and frustrated that he doesn’t seem to understand the enormity of the relationship he has with Klaus,” Plec says. “He actually starts the episode off by agreeing with her, and telling her she’s right. It’s a really sad scene between the two of them. They have to acknowledge that they love each other so much, but right now he’s not in a good place. He’s got to deal with that, and of course, it all happens on the morning of her birthday.”

The next few episodes will find Caroline grappling with the reality that “normal” is a thing of the past, teases Accola. Luckily, as per usual, she bounces back quickly. “Caroline doesn’t stay depressed for too long, ever,” she says. “She bounced back pretty quickly from her father torturing her. But Caroline has become a strong young woman in her own right, so I don’t think she would let herself stay down too long. … She definitely doesn’t go all Ripper.”

And her better mood could have something to do with Caroline’s birthday swag. “Caroline does get a very lovely birthday gift,” says Accola, declining to elaborate on the identity of the present-giver. “You will see.”

But even though Caroline is relatively quick to recover from the blues, Accola isn’t so sure she will stay so stable. This season has seen some of Paul Wesley’s best work as he took Stefan onto the dark side, and there’s no telling when Caroline could follow suit. “If you would have asked me during season 1 if I saw Caroline becoming a vampire, I would said no. So it’s the same thing,” she says. “I have no idea what the writers have up their sleeve. So right now, no. But in the future, who knows

(Additional reporting from Shaunna Murphy.)

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