You could deny him. There's an upper limit to how much you need to consume in any given time. If you're eating enough from other sources he won't have a reason to offer it. He does so for your sake, not his own.

[The stillness immediately after feels longer than it is. The truth is, it doesn't take long for Alhaitham to come to the conclusion.

He peels off the wall and circles to stand in front of Midnight's sitting form.] Anyone's blood will do as long as it's human, won't it?

How much of it do you need in a day, Midnight?