"It can be," Elspeth agrees. "When it works out it's nice, though. And mate bonds - and imprinting ones - are immune to some magic that could mess with other relationships."

"At least mate bonds are automatically symmetrical," she says. "Or they are if both parties are vampires. What happens if a vampire mates to someone who won't or can't turn?"

"Then the person who's not a vampire is not affected," Elspeth says. "It's very sad for the vampire and pretty awkward for their mate, and we have to be watchful to make sure the vampire doesn't do anything drastic. Wolves tend not to do that, fortunately - they're not as possessive about it, although if their imprints are in danger they will definitely do something about it." Jake pats her on the head.

"It just seems like a really inefficient system."

"As far as we know, it wasn't designed - it's just how vampires and werewolves work."

"Well, no wonder it's inefficient."

"Of course," laughs Elspeth. "We just work with and around it."

"Dare I ask what 'drastic' means, anyway?"

"Manufacturing a medical emergency, or doing something coercive to get their mate turned, or just biting them themselves and turning them without anaesthesia - basically, the object of a rejected vampire mated to a human is to get their mate turned so everything will be nice and symmetrical. If they mate on a hybrid instead and that can't happen, they just go kind of... stalkery."

"Charming."

"There's an extent to which they can't help it, but they do vary in how bad they get, so we have to hold them responsible anyway," sighs Elspeth.

"How bad exactly does that tend to be?"

"It ranges from disconsolate pining - harmless - to suicide - legal, especially under the circumstances, although we do try to encourage people to wait a year or five in case their mate comes around - to harassment and pestering and trying to find any means they can of bringing pressure to bear - sometimes legal and sometimes not, depending on how overboard they go - to various combinations of forgery, carefully calculated degrees of assault to try to force turning either to save life or reverse disability, kidnapping, that sort of thing - not legal at all."

"Ouch," says Libby. "Remind me not to visit. 'Kidnapped by lovesick vampire' is not on my list of dream vacations."

"It wouldn't be a random vampire. The relationships usually work out, even when one party stays not-a-vampire, if they give it a chance; they're people who are suited to each other. And we do protect vampires' mates who don't want to. But sure, you don't have to come home with me." She shrugs and downs the rest of her golden bubbly and orders another.

"Suited by personality, if not by species?" she says dryly.

"Well, also by species a little bit, in the sense that vampires don't seem to mate to werewolves and werewolves don't seem to imprint on full vampires," Elspeth says. "At least unless someone changes species after the fact; both phenomena are very durable once established. I'm not otherwise sure what you mean. It's not like interspecies relationships are doomed or always a bad idea or anything except that you should avoid getting attached to someone who hasn't mated-slash-imprinted but still might."

"I don't know, I just can't imagine half a mate bond being a comfortable start to a relationship. But maybe I'm approaching it too analytically."

"Not everybody seems to have mates at all - there are vampires who've been around for thousands of years who don't have them, and there's a witch who copies powers who's repeatedly tried a precognition power that showed its own witch her mate right away, and the copier wasn't shown anyone. So whatever's going on, it's not for everyone," shrugs Elspeth.

"Fascinating," says Libby.

"It is. We don't know that much about it because R&D can't perform any experiments, only observational studies, but we're paying attention."

"Paying attention is always a start," Libby says agreeably.

"What do you do, in your vampire-free 2005?" Elspeth asks.

"I'm a mathematician," she says. "It's more fun than it sounds."

"Ooh. The fellow who absorbed the memory payload I have ate some mathematicians but I don't know how within date their educations were and I haven't been keeping up with the field."