Here is another bit of Supernatural/Doctor Who/Vampire Diaries crossover. I'm insane, someone please stop me.

Vampires and Vortex Manipulators

It was an accident that River Song ended up in Mystic Falls. Well, the second time it was an accident, the first time supposedly wasn't. The Doctor still stuck firmly with his claim that it was completely intentional when they landed there in the 1860s, right in the middle of a massive Vampire hunt. Then again, maybe it was intentional. It wasn't the first time they'd run into that bitch, Katherine, so maybe he had landed them there on purpose. But then, River knew the Doctor. It was infinitely more likely that it was just some intergalactic coincidence.

The second time she lands there, sometime in the 2010s, it's completely by accident. Vortex Manipulator malfunction.

There was something strange about Mystic Falls. There always had been, what with their rich history of Vampires and Werewolves and Witches (a history much more extensive than the books told). River liked strange. The moment she realized she was in Mystic Falls, with all its Stepford ominousness, she was prepared for weird.

What she was not prepared for, was running into Katherine Pierce.

"What are you doing here?" River asked. "I thought you were dead."

"She's not Katherine," an all too familiar voice said from behind her.

River turned, and couldn't help but smile. "Damon Salvatore. You haven't aged a day."

"Well, yeah, Vampire," he deadpanned. "How do you explain your eternal youth?"

"Time travel," she shrugged.

"Uh, Damon?" Katherine asked, clearly confused by the circumstances. River saw it then. She wasn't Katherine. Not even close.

"River, this is Elena Gilbert. Elena, River Song."

"Hi," Elena said, still confused.

"Hello," River smiled in a way that made Elena feel rather uncomfortable. "You look just like her."

"What are you doing in Mystic Falls, River?" Damon asked.

"Curiosity?" she offered.

Damon didn't seem amused. "It's good to see you and all, but we've got enough trouble on our hands as it is. We don't need any of your trouble, too. Beat it."

River tisked. "But we always have so much fun," she said.

"Not this time."

"Ooh," she frowned, turning to Elena. "You've turned him all goody and domestic. I'm not sure I like it." She turned back to Damon. "You're in luck. This whole 'small town' thing puts me on edge, and I didn't come here on purpose, so, I suppose, this time, I'll get out of your hair." She pulled back her sleeve and tapped at her Vortex Manipulator. She paused and looked back up at the two of them. The Vampire and the Katherine look-alike. She wanted to warn them. She wanted to tell them what was coming.

"Two boys will come to town soon," she wanted to say. "Might be a few weeks, maybe a few months, but they'll be here. They don't see things like you do. You have to be careful. You could be best friends with them, but it won't be easy. They won't trust you. They'll hate you. They'll try to kill you. They might succeed."

But she couldn't say anything. The Doctor would kill her if she changed this town. If she could change it. Maybe all the warnings in the world couldn't change this place. A fixed point. In which case, her words would only serve to put them on edge.

"It's scary how much you look like her," she said instead. And then she was gone, as if she'd never even been there.