The lady is flawless; she walks with grace and speaks in a language of melodies and songs. The sight of her converts him. The enchantress, with only one spell, binds him.
Day and night he follows her call and reality becomes only what her voice commands. She is pure and green, and the poison in his mind don't let him think otherwise.
Yet he knows, in his heart, of the wrongness taking hold of him. He tries to escape only to have his mind bathed in lies once again.
When the evening comes, he's gone. The Black Knight has returned.