Two ideas:
Doesn't Give a Damn Dumbledore:
Dumbledore is tired. He defeated a Dark Lord, he was the beacon of hope when Voldemort first appeared, and after his miraculous disappearance, everyone was clambering for him to take the reigns.
And people keep on asking for more. They want him to run the whole of Wizarding Britain, be the liason to the greater wizarding world, and run a damn school at the same time.
So he decides, fuck it. He's done with the wizarding world, even if they won't leave him alone. He's going to do what he wants until they finally let him retire, or he dies.
So Dumbledore runs the school like his own personal amusement park, and any sort of legislature he has to deal with he does whatever will cause the most chaos. Sadly, his
reputation means that they either brush it off as Dumbledore being Dumbledore, or he sees something else no one else does, and it's brilliant beyond words.
I just like the idea of something like this appearing at the end of the first book:
"Fuck wizards Harry."
"I beg your pardon?" Harry asked the Headmaster.
"I'm serious, fuck them right up the ass."
"I'm afraid I don't really understand sir."
"Seriously, I put a ravenous beast in the castle, with no safe guards aside from a warning that it would result in your death, and a rusty old lock. What kind of parent just accepts something like that? Not only that, but I was deliberately baiting the greatest threat to Magical Britain since Grindelwald to come into a place, and no one says a word! The teachers all went along with it as a great and clever idea! I expected Professor Sprout to say SOMETHING about endangering students liek that, but not even a peep!"
"I've hired a known Death Eater to teach children, and they think it's fine! I let Snape get away with almost anything, and no one says a word! I'm staring to think the only option is to let students start dying, or at .least getting maimed. Maybe I should hire Hagrid as a teacher. He doesn't seem to understand the idea of dangerous animals..." Dumbledore trailed off.
"Hagrid's not... that bad." Harry tried to defend his friend, but a look from Dumbledore told him it was futile. The Headmaster was more than aware of Hagrid's proclivities.
"I just want to retire, but every time I mention it, everyone starts freaking out. They keep saying they can't manage without me, that I'm the only thing keeping things in order, and won't let me get a word in edgewise!" Dumbeldore groaned.
"I've disappeared three times in the last ten years, just up and left, hiding behind the best wards I could find, and they STILL won't leave me alone! They always track me down, and beg me to return until I can't stand it any more! Even being stuck here is better, because I get at least a modicum of peace and quiet!"
"I'm sorry sir."
"Harry my boy, you will have it just as bad, if not worse. Why do you think I left you with relatives that hate magic? If I left you with some wizarding family, you'd be drowned in fan mail on a daily basis. You'd never know a moment's peace!" Dumbeldore said, his voice grim.
"Couldn't you have left me at an orpahage then?" Harry asked.
"I could have, but I knew your relatives were bastards. I was hoping Arabella would go to the press about the terrible conditions you were raised in and I would get sacked, but she assumed it was for the greater good or some such stupidity."
"Arabella, you mean Mrs. Figg?"
"Seriously, if anything crazy like this happens again next year, just fake your death. It's better than the amount of bullshit you'll have to put up with for the rest of your life." Dumbeldore said, his eyes losing their customary twinkle. "Promise me Harry, perhaps at least one of us can get out of this living hell!"
Harry nodded, not sure what else to do. Perhaps the wizarding world wasn't as great as he thought it was. He had been nearly killed half a dozen times this year, and everyone seemed to accept it. Maybe he would be better off on his own, it wasn't liek he couldn't afford it.
Evil Founders:
The Founders were Pragmatic Evil.
Hufflepuff: Was the actual anti-muggle member of the founders, wanting to join all of wizardkind together so they could avoid the muggles until they were ready to exterminate them.
Ravenclaw: Wanted the opportunity to conduct research without worrying about morality, collateral damage, and the death of idiots. All just necessary sacrifices on the road of knowledge, especially those muggles that Helgha hated so much..
Slytherin: Probably the leader of the four, he wanted to unite all of the wizarding world under his rule, forging an empire of unsurpassed power, that all magical life would bow down before.
Gryffindor: Wanted the opportunity to test his mettle against worthy opponents, even if he had to train them up himself. Also an opportunity to explore the power of more devastating war magic, the kind that would be used to raze unsuspecting towns and villages.
The school was conceived so they would have a base of operations, ready recruits, and an opportunity to shape the wizarding world without being too overt about it.
Of course, running an academy of evil probably upset a few people along the way, like Merlin for instance. Rather than let their ambitions be crushed, they decided on a fall guy. Slytherin drew the short straw, and the rest of them tarnished his name, claiming all sorts of deception, manipulation and the like to preserve Hogwarts, all the while making sure his legacy, the Chamber of Secrets was preserved. Rumors of it were spread around so they would have a ready source of explanation for any evil happening in their school, it was probably some Slytherin legacy!
As the other founders aged, they probably built their own versions of the Chambers, ready for the person with the rigth mindset to continue their work.
Thoughts?