A demon

Zane took a step back when Ava got too close. There was something about her that made him apprehensive. It wasn't there when they had met in the afternoon, but it was there now.

Suddenly, she stretched out her hand, targeting his neck. It moved so fast, like a snake snapping at its prey. But this was night, Zane was much stronger and much more in his element at this time.

He stepped back fast, the fingers missing by only a few inches. He looked at her hands, and there he saw glowing purple markings.

He had seen those markings before; he knew them. 'Demon marks. She's a demon'. The sudden realization made him understand why he had been apprehensive. From what Lucy had told him, demons and vampires didn't go well together.

Without missing a beat, he pulled out his dagger, spun it, and slashed. His movements were fluid and sharp, going straight for her neck.