Destiny.
Angelus enjoyed challenges.
Murdered priests were his trademark. The thrill of sacred ground and crosses which were not enough to stop him... He'd show them Hell on earth and absolutely no reassurance of a Heaven beyond.
But he grew easily bored too.
Of course, Fate always favoured her dearest son.
Now he was curious about his newest challenge.
The delicacy of her voice, the fear in her words, the sweetness of her pleas... Those beautiful eyes full of faith and resignation...
...and her visions. Devil's work or God's gift, it didn't matter. Angelus had to possess her.
It was destiny.