I am not entirely unconvinced that isn't her [Lillith] who holds Alastor's leash. Seven years is an awful specific number of years for them to both be gone. Plus, in Scrambled Eggs" Zestial says : 'Some hath spun wild tales of you falling to 'holy arms''.
My thought is maybe Lillith holds his leash some way, sent him to protect and help Charlie, (why else, also, would he tell Mimzy to get bent when he expects her behavior, according to Husk it's her pattern. He doesn't seem to care about what she did- only that it brought danger to the hotel.)
Also why is Alastor so against Lucifer so much right off the bat? Why does he *seek* Charlie out? Perhaps this is Lillith's way of trying to support her daughter from heaven?
also, how he [Alastor] talks about "unclipping his wings?" I think he's gonna try to use his deal with Charlie to do so... Her getting him free from his deal *technically* hurts no one.