What gives me the most anxiety is the fact that Baal has been shown to be the "knows and controls everything" type of character, meaning whether or not Fenrir is directly allied with Baal is irrelevant because Fenrir is absolutely doing exactly what Baal wants.
But that also gets me worried about how the author will eventually make Baal fail since it's very easy to just pull something like a "The guy who planned everything didn't plan for the human to make friends with the demons and now power of friendship defeats evil" kind of ending and I would be very disappointed if that's what happens.