Mr Quinn appears at one point, at the very beginning of the first episode, so he is EXTREMELY minor. He simply is used to show the mean nature of Blackbird, as he kills him for no apparent reason, because he wants to know who Mr Quinn's "buyer" is. (The Buyer, by the way, is not seen or heard from in the first chapter, however, he makes a small easter egg at least 3 times in every chapter, whether it's a thug talking about him or a sign on the board, but he does not have a main role until the last chapter).