She was lonely, looking for someone like herself. There was no one. She was unique, unusual... a freak. But a freak with a difference. She could make herself a mate.
She picked him: because he'd gotten her to laugh when she'd been feeling down, because of the strength under his gentleness, because his kindness would make such a delightful contrast to the single minded call of the hunt.
Easy to arrange an accident, a slight cut that she could kiss better. After that, all she had to do was wait for the full moon.
In the moonlit night, Xander howled.