Dear Padfoot,
You can't imagine how much your letter surprised me! You careless, restless, TRUEST friend. I miss you so much!
I know what I am and I would never hold it against you that you thought of me accordingly. You already did far more than what I could have ever asked for, and that's a fact.
I honestly don't know which of you betrayed Prongs and Lily, as I never suspected either of you to commit such a horrible deed. But then, that's why I'm not an auror anymore. I'm too soft for the job.
I'm doing relatively fine. For a while I left for a muggle lifestyle, because they weren't aware of the danger I meant to them. It was easier to hide, than to face all the prejudice on a daily basis. In other words (Albus' words), I was on the run from myself.
I'm taking one last chance, now that finally a potion was discovered. I won't worry you with the details, but I will get my medication, and be able to harmlessly sleep through the worst three days. You won't guess where: I'm going back to Hogwarts. Someone needs to be the Defence Against Dark Arts teacher, and even if the position is 'jinxed', it can't be worse than I already am. And I can also promise you to look after Harry, he'll start his third year there. He's been the seeker of the Gryffindor team since first year, and a hero of the school on his own right. James would be so proud.
Dear Padfoot! I know it's hard not to chew on old things where you are, but I hold nothing against you. Mind you, James wouldn't, either. Trust me on this. You two were the greatest troublemakers of wizarding history. His loss must have hit you even worse than me.
All is forgiven, Marauder. And by all, I mean all.
I wish I could do more for you.
Yours,
Moony
P.s. Thanks for the bite mark idea! I don't have any magic-bearing ink. It must be hard with those eyeless monsters around. Have you heard that Barty Crouch got kissed last night? What a horrible fate! I trust those beasts around you are better disciplined. I'm really worried. Is there a way you could defend yourself?