Pathos vol. 1 (Yaoi manga)

A has been raised in happiness by the beautiful young men K and J. To thank them, A adores them as older brothers and grows innocently attached to them. But as A grows J becomes colder to him with each passing day. The truth is K and J are immortal vampires, and J has kept his distance because he may become unable to resist the scent of the fresh blood of the growing A.