Dear Professor McGonagall,
I am replying to your letter in order to clear up several of your miscomprehensions.
Firstly, I am not going to attend Hogwarts under any possible circumstances.
Secondly, I am not 'eager to begin my magical education.'
I have already been learning magic for the last three years, and I am just now beginning to grasp the principle that the actual use of magic is to be avoided whenever possible. A precept that I am absolutely sure that nobody at all in your wizarding world, yourself included, is ever able to grasp, considering how buggered-up your society appears to myself.
Where exactly did I learn that, to you, obscene rule?
Why, at the Unseen University, in the city of Ankh-Morpork, the Discworld, somewhere in outer space.
Never heard of the place?
Good. If you don't know about it, you can't find me.
Oh, and don't bother asking the owl. Considering how that bird landed with your letter right in the Archchancellor's soup while he was at dinner, you're extremely lucky he didn't turn your messenger into giblets right then and there.
Now if you'd actually like an explanation, it all began a month after my eighth birthday, when I was hiding from my obese cousin Dudley and his band of bullies occupied with their latest round of 'Harry Hunting'. Which was just another example of the hellish life I was stuck in with my relatives who totally loathed wizards and magic, only to have dumped upon them back then a baby who was the child of a wizard and a witch, and already possessed an extremely high level of magic. As a result, for the next couple of years, I got treated by my uncle, aunt, and cousin as some kind of freak and was put to work by them ever since I started to walk, having to do all the cooking, cleaning, and gardening at their home, and in effect being their absolute slave.
By the way, I've eventually found out that it was both you and your idiotic superior who thought it was an absolutely bright idea to drop me off at the Dursley home. Actually, regarding Albus Dumbledore, a better description would be 'superior idiot.' The pair of you should be utterly thankful that just as you can't get to me, I can't get to you, either. Damn it.
But I digress. Anyway, as I said before, I was hiding, and I picked the local library to do that, since I was sure Dudley and his friends would never dream of entering the place. I was perfectly right, and as I enjoyed the peace and quiet among the bookshelves, my attention was caught by something very odd happening there.
Quietly, without the least bit of fuss, books were being pulled backwards in their lineup along the bottom of one shelf, to disappear into thin air for a few seconds, only to reappear back on the shelf, completely intact. Naturally, I went over to investigate this, since anything else was better than going back to the Dursleys. That kind of thinking also made me grab hold of the next book about to vanish, which resulted in me being pulled right into and then through the bookshelf, without being harmed at all.
Though, some people might have become a bit mentally scarred by suddenly standing in front of a shocked orangutan holding onto the same book I was still gripping. Hey, I already had lots of physical scars, thanks to the wonderful life I had going on with my three blood relatives, so all I felt at that time was total fascination.
It eventually wound up with me adamantly refusing to return to Little Whinging, no matter how much the Librarian gestured. He finally gave in, particularly after he went off into L-Space for a few minutes, though I'm sure it was a lot longer than that. Incidentally, he's not too impressed with the level of security on the Restricted Section in the Hogwarts Library, so you might want to upgrade this. Anyway, while my new stepfather was at Hogwarts, Gringotts, the Ministry of Magic, and Diagon Alley, he found about everything.
The wizarding world. My parents. Voldemort. Dumbledore. That damn prophecy.
The end result was a very grim primate adopting me, getting that horcrux out of my head and dropping it off the edge of the Rim, and enrolling me in Unseen University to give me a fighting chance on how to contain my magic. If you're wondering how an eight-year-old could possibly get into a magical school, let's just say that they really want to keep wizards under control here, so over the last thousand years, it's occasionally happened for someone just starting teething to be brought into the university, along with their binkie and sippy cup.
So, here's the main point of this letter: I'm not moving to Hogwarts, and if you try to force me to leave my home and attend that place, you're really not going to enjoy what happens to you, Dumbledore, and any others of those total berks there who won't leave me alone. You've got a few wizards. I've got the entire staff of Unseen University, all of who want to stay on the good side of the Librarian, plus as a naturalized citizen of Ankh-Morpork, the Patrician would look upon with intense disfavor anyone at all kidnapping one of his subjects.
In conclusion, Voldemort's your problem. You take care of him.
You've been warned.
Harry "Oook" Potter
P.S.: While re-reading this letter just before sending it off to you, I've come to the conclusion that it might be a little harsh. Excellent. Still, in memory of my parents, I'm going to offer you a little help, which will come along with this note. I've been assured by Rincewind that if something like it managed to defeat an actual sourcerer, a copy should be more than enough to take down a minor prat like Riddle. Good luck in finding someone to use it. I suggest Snape, or someone equally disposable.
As she then dazedly dropped the letter she'd just finished reading onto her desk at Hogwarts, Professor McGonagall stared with absolute incredulity at what also rested now upon this piece of furniture: a child-sized, extremely grubby sock that contained a half-brick.