Julie Plec has hinted at a future crossover between The Originals and The Vampire Diaries.
While the executive producer doesn’t see the two universes merging “in the next several months,” she remains open to the possibility of a crossover happening at some point in the “life of [The Originals],” possibly in a renewal-contingent third season:
“I do think there is potential at one point for us to see [Caroline] on The Originals. I just think it’s going to take [her character] getting to the right place whereby that feels like an organic choice, and that might take some time, and I know that’s the kind of answer that not a single fan in the world is going to like very much, but you’ve got to get [the characters] there.
I don’t see Caroline in the New Orleans universe at all right now, it doesn’t fit. [But] in the life of the series it’s definitely a possibility, in the next six months probably not, but we are sitting around talking about a crossover, not with Caroline but with the Vampire Diaries universe, but it’s too soon to tell [if it’s going to happen].”
HT: The Original Vamps Club