I forgot to mention - David Mitchell would have magic powers. That would be how it was possible for him to impregnate Robert Webb. He kind of did it accidentally, and then did some sort of highly amusing rant (of the sort I can't write) about how it's just his luck that when he actually does turn out to have magic powers, they consist of unintentionally impregnating another man, and teleporting them both to the middle of a war full of people who want to kill anyone with magic powers.

Sadly, I get all nervous trying to write David Mitchell, and I suspect Riona would only be interested if Charlie Brooker was in there somewhere. But believe me, this isn't the weirdest idea ever discussed here.