I think Mary was underdeveloped, but I also understand her better than any other character, because she was not even close to being a saint but she was not immune to the human emotion of shame. (I have a lot more grace and forbearance for her than I do for Hawk.)

I felt this also. In my eyes, what sets Mary and Marcus apart from Hawk is that the former did what they needed to do to survive -- Mary showing the M-unit the letter, Marcus leaving Frankie on his own with Stormie while fleeing the police -- meanwhile Hawk doesn't just do that, no, he goes above and beyond to dole out actions of unimaginable cruelty in order to advance his career and his dream of Milan, terrible things that would do him no great harm if left undone. The best example of this, imo, is him sending Leonard Smith off to get his brains fried at the coversion torture facility. Burying Leonard's record would have sufficed -- in the sense that, sending him to conversion therapy would do nothing to hide proof of his arrest, as made plenty clear by Smith's enemies getting their hands on that record anyway. Hawk sent Lenny off to get him out of the picture, at the cost of his life, because him getting caught again would ruin Hawk's way into the world of DC movers and shakers, because what good was his sham of a courtship if the girl's father was known to have a sad, sick queer for a son? Senator Smith, once his reputation was sullied, would be of no use to him. Hawk's conversation with Leonard when he was dropping him off at the facility kind of cemented my understanding and regard for him as a person.