Dear Mother,
I didn’t want to tell you because I know it upsets you, but Sirius has been swearing at me. I promise I didn’t start a fight with him or anything like that. You believe me, don’t you? He just came up to me and started saying rude words, and I told him I was going to tell you what he said, but he didn’t even care. I was going to tell Professor Slughorn, but I thought you’d rather I told you. Did I do the right thing?
I think it must be because of his stupid new friends, because he never used to use bad language, did he Mother? I don't want him to be friends with them. Make him stop.
Your son,