A/N For those of you waiting for A Legend to be updated, I promise it'll be soon, but I've got the opposite of writers block, way too many ideas, and I want to clear my head before I write chapter six.
To Grow Up
Sirius never believed James when he said he was over Lily, because he wasn't. If you get over someone you do not change your entire attitude, life prospective, ideas of wrong and right, and you most certainly did not undergo major changes to your level of responsibility.
No, if you were over someone you generally actually got over them. You get on with your life, you go out with new, different people, you move on, you do not under any circumstances become Head Boy to fit her idea of perfect. That was a key example of what not to do when faced with getting over people.
So it was understandable that Sirius didn't buy it, because he was right, James wasn't over her. Sometimes Sirius thought that Lily didn't really love him, just the person he'd turned into for her, but then he'd see her eyes light up as he walked in the room, and he'd know, he really did love her.
So maybe he was being depressing, when he thought that he that she really didn't love him, and that he had changed just to please her. It was easier than facing the reality that James had grown up, because if James grew up, he would have to grow up to, and growing up had never been a part of his plan, not really.