Disclaimer: Buffy and the Slayers are owned by Joss. Petrova and the Simpsons are owned by Noel Streatfeild's heirs. I own nothing but the words.
Petrova was helping out at Mr. Simpson's garage when it happened. She'd been trying to tighten a lug nut, when suddenly she tore it off the bolt and the wrench went flying. She stared at her hand, then climbed out from under the car and stared at it again. Looking around for the wrench, she saw Mr. Simpson holding it and smiling.
"It's quite all right," he said. "I've been expecting this."
After they cleaned up and Mrs. Simpson plied them with tea and biscuits, he looked at her seriously.
"You see, Petrova, our world is older than you know…"