[Evidently, this man does just... give things to people. Which is strange to him. Does he really expect nothing back?

Still, Alucard dislikes the feeling of being in debt.]

As I understand it, Cerberus is just doing his job.

[look it's from one dog to another

There's a pause of consideration, then he pulls out a dark looking lyre, offering it to Zagreus.]

...Listen. I've no need of this any longer. It is what I used to find my way to the Underworld. I don't really know how it will benefit you in particular, but perhaps you will find some use for it.

It's not nectar, but certainly it has a unique value on the surface. So. There is that.