Dear Arthur,
It's been too long, and I apologize for writing only when I need a favour. I hope you'll enjoy this one, though.
Has Charlie told you? I hope so. About the SORAS virus. And that I'm affected?
I've been living in a flat that Severus and I shared for a time in a Muggle area of London, and I've managed to get my hands on a fair sum of Muggle money via Gringott's. My neighbours assumed I was the indulged/neglected son of someone wealthy, allowed to run loose -- not unheard of in London, by any means, apparently. They responded to me in various ways, but no trouble that some combination of good manners, good judgment, and cash couldn't smooth over, up until quite recently.
The Ministry has been harassing me about Improper Use of Magic, and about being "unsupervised", and I've had trouble in Diagon Alley (not with Fred and George, of course), especially these past few days, now school has started.
I'm apparently down for Hogwarts.
Anyway, to make a long story short -- if it's not too late for that already -- I'm afraid I had to give the Ministry a name. And since neither they nor I wanted that name to be Dumbledore, I gave the name Weasley. Purpureous Flavus D. Brian Weasley. It's a mouthful, I know, and I know that you and Molly would never be so pretentious, and would have settled for Brian, but I thought maybe if I was less closely related - perhaps a great-nephew, or a second cousin twice removed, assuming those aren't the same thing.
The reason I bother with these details is that it seems I need to appear before the Wizengamot, and based on experience I think it will go much better if I do so accompanied by a blood relation. Do you think you could send MLE or IUM a message, explaining that I (Purpureous Weasley) am your (great-nephew or something plausible, where my parents could be gone for some not-excessively-tragic, though perhaps disreputable, reason), and assuring them that you will escort me to the hearing tomorrow morning at ten o'clock? At least they told me it was at ten, but you know how they can be. I don't imagine there's any tampering going on this time, though. They just want to be assured that there won't be any trouble.
Which is too much for any of us to ask in this life, but that's the Ministry for you, isn't it.
I'm hoping that Fawkes will carry this, now that he knows I'm safe. I've moved into Lake Cottage for the moment with Severus and his family. I don't think the Ministry needs to know that - all the magic here will muddle up the trace on any spells I attempt, I'm sure. They'll assume you and Molly have retrieved me, and make you promise to send me up to school post-haste.
I think that's all. I suppose I should floo over from here in the morning, so that we can arrive at the Ministry together. Just let me know if and when you've told the Ministry you're responsible, as up until then they might be minding the floos for me. I don't trust myself to make a portkey at the moment, and I certainly don't have a valid license to apparate.
I hope this is all right, and I look forward to seeing you. I won't ask you to give Molly a kiss for me this time, as that sort of thing seems to have changed radically due to my age, but I think a hug would be all right, if not terribly convincing.
Your friend - and apparent relation -
Albus Dumbledore