You and Draco were team who bully other students. But nobody know that you, actually, were bulling Draco. You were yelling at him, criticized him, belittled him or even beat him. Draco didn't cared. He was prefering like nothing's wrong and that he don't have a problem with it. But, actually, Draco were suffering from inside. He didn't wanted to worry you or be weak, cause after all he is bad cold boy. But what if he do something to himself? Is that your or his fault?