Albus Dumbledore

Professor Albus Percival Wulfric Brian Dumbledore, Headmaster of Hogwarts, Order of Merlin (first class), Supreme Mugwump, Chief Warlock and Grand Sorcerer , is a wizard and the Hogwarts as of January 1993.

Past
Professor Dumbledore's past up until 1991 is assumed to be identical to that of his canon self.

1991-1992
During that school-year, Professor Dumbledore was the mastermind behind the protections put around the Philosopher's Stone of his old friend Nicolas Flamel. He somehow placed it within the Mirror of Erised, from withing which he thought Tom Riddle's agent Professor Quirrell could have no way of getting it, as only a sincere desire to get the Stone for its own sake rather than to use it would release the Stone from the Mirror. He temporarily stored the Mirror in an abandoned classroom before moving it to the Third Floor Corridor where he had had his fellow Professors install various other protections meant to delay an intruder.

On Halloween, when Quirrell announced there was a troll in the dungeons, Dumbledore ordered the Heads of House to escort their students to their Common Rooms (overlooking that the Slytherin Common Room was in fact located in the Dungeons). He, meanwhile, stayed behind in the Great Hall and witnessed Peeves's beatdown of the troll. With the help of Severus Snape, Dumbledore finished the job by using a powerful variant of the Stunning Spell on the troll to knock it out altogether. He then attempted to ceremoniously thank Peeves, who in turn tugged on Dumbledore's beard and flew away.

For Christmas, Dumbledore "gifted" James Potter's Invisibility Cloak back to Harry Potter, albeit anonymously.

Towards the end fo the year, Dumbledore was called away from Hogwarts, to London, on what turned out to be a wild goose chase. He came back to find that Harry and Hermione (aided by the Basilisk, although he wasn't aware of that at the time) had come after Quirrell in his attempt to get the Stone, and, moreover, that Quirrell had been possessed by Tom Riddle all along and that the both of them had somehow ended up Petrified.

Preferring not to trouble the Ministry with the fact of Voldemort's survival since he was already dealt with, Dumbledore decided to cover up the incident. At the Departing Feast, Dumbledore claimed that Quirrell had died of a particularly serious case of Vanishing Sickness (they'd reportedly "only found his turban") and reinstated that the Third Floor Corridor was still out of bounds — this was no longer as a hideout for the Stone, which he had returned to Flamel, but as the keeping place of the petrified Riddle and Quirrell.

Summer 1992
Dumbledore spent the summer of 1992 directing an overhaul of the Third Floor Corridor's defences, in light of the old ones having been breached by a couple of first-year students.

1992-1993
On Spider Day, Professor Dumbledore welcomed the Centaur Herd upon their entry into Hogwarts and attempted to parlay with Magorian, trying to understand why they had come. When the Acromantulas attacked, Dumbledore was, of course, among the wizards who helped in the battle, putting his enormous magical skill to good use, attempting to subdue rather than kill.

Even after the battle was seemingly over, he pursued the fleeing Acromantula soldiers into the Forbidden Forest and found Mosag, whom he bested and captured in unknown circumstances. He then talked with Aragog, impressing upon him the importance of keeping his people in line in the future, and positioning himself as backing up Aragog's rule against Mosag in the eyes of the other Acromantulas.

Later, Dumbledore came to greet Hermione Granger when she woke up from her Acromantula Venom-induced coma, and answered her many questions about what had occurred during the battle. More generally, the aftermath of the battle was a mess that was his to sort out; he had to prevent Hagrid's arrest and the Acromantula's extermination by the Ministry of Magic while simultaneously keeping Hogwarts open and avoiding offending the Centaurs. In the commotion, he had no time to seriously look for a new Defence Professor and was instead forced to give the position to Alexander Max, the Ghoul Studies teacher.

For Christmas, Professor Dumbledore decided to organize a splendid party so as to make up for the misery of Spider Day. First, he arrived in the Great Hall dressed up as Father Christmas, escorted by the Hogwarts Elves, playing the part of Christmas Elves. The Elves were carrying various presents each meant for one of the people residing in Hogwarts at the moment. One Elf in particular was sent to the Chamber of Secrets with a present for the Great Basilisk: a Basilisk-sized pair of goggles enchanted by Dumbledore to block the effects of the Basilisk's Gaze, thus allowing her to see and be seen. At dessert, Dumbledore, together with Professor Flitwick, participated in a magic-enabled "spectacular light-show".