It isn't his intention, of course, to blackmail the poor boy. It's simply that Samandriel's case is a delicate one, and Hannibal wants the best for someone who means so much to Abigail. That, and it's an interesting case. And Hannibal does enjoy interesting cases.
"I might be, at that," he concedes, nodding his appreciation. "I am free Wednesdays after seven pm, if that's convenient for you."