He's a powerful magical creature who was bound in servitude to the Abhorsens a long time ago, as a punishment. The only thing he'd want from me is his freedom, but he'd be very dangerous if I let him go. To me and to everyone else.
I try not to ask very much of him. Most of the time, he just sleeps. The rest of the time, all he wants is food, even though he doesn't need it. I've given him some of my fish, every once in a while, when he's awake.