The Fairy Godfather

The day Paul's daughter is born, a smiling stranger with pointed ears visits the hospital to make him an offer he can't refuse. It's a dangerous world out there. Especially for children. But he can give Paul something any parent would do anything for: the certainty that his child will be safe. And all it will cost is a single drop of blood. For now. But prices always go up... This short story is 12, 000 words long.
It is also available in Devil's Bargains, a short story collection.