The give & take relationship. Hellsing (Dhampir) gives his body to Tayuu, while Tayuu gives Hellsing his body fluid. When Tayuu and Hellsing meet, all they do are to argue, and to have very kinky sex...
"I want to touch" "I want to dominate"... Tayuu doesn't understand the reason why he wants more. And Hellsing can't create a "beloved person" because of what he is....