Kaze to Ki no Uta Sanctus: Sei Naru Kana

Is it holy?

Synopsis

Son of a viscount and a Roma prostitute (both deceased), Serge is intelligent, sweet, talented, and alienated by his family due to his heritage. Upon being sent to his new school, he rooms with Gilbert Cocteau, a gorgeous loner of a boy who sells his body for reasons unknown. Serge's attempts to reach out to Gilbert fail spectacularly, and yet there is something in both of them that attracts them to each other.