Minerva McGonagall didn't know her old legs could move so quickly.

She had been sitting at her desk, thinking about the odd encounter she had just had with Harry Potter, Hermione Granger and Ronald Weasley - a trio who had proved to be troublemakers like few she'd seen before. And it was just their first year.

While the entire conversation had been a bit on the strange side, one particular point kept coming up. If a group of, albeit unusually intelligent, first years had been able to reason out that the Philosopher's Stone was hidden on the third floor… Was it so far a stretch to believe that someone with ill intent had figured out the same thing? Without Dumbledore in the castle, it was up to her, as the Deputy Headmistress, to keep her students safe, and protecting the stone definitely had her student's welfare in mind.

She decided to set her mind at ease by going for a stroll to the third floor, just to be sure. She began to get an uncomfortable feeling in her stomach when she saw the door, which was supposed to be locked, sitting slightly ajar.

However, she was in no particular rush until she discovered the Cerberus deeply sleeping and the trapdoor wide open.

As she levitated herself down the pit of Devil's Snare, which had a clear hole burned through it, her heart began to race faster and faster. She allowed herself one brief pause, just long enough to whip out a patronus to send a message to Filius Flitwick, the member of staff she trusted most to cover her back in this sort of situation. With her Cat patronus gliding away gracefully, she continued her race to catch up with whatever was bulldozing through the protections.

While she navigated her way expertly through the room of flying keys, she began to become more and more disillusioned with the true protectiveness of the 'traps' they had set. With a wave of her wand, she easily stopped the flying keys from attacking her. Another wave saw the door being blasted off its hinges, allowing her through. All in all it took under thirty seconds to clear the entire room.

Upon entering the chess room, she let out an involuntary shriek at seeing the crumpled form of the youngest Weasley boy. A quick diagnosis charm alleviated her fears that he had been killed, but the fact still stood that he was injured by the trap she herself set up. She cast a quick transfiguration to turn a loose stone into a stretcher and levitated him onto it, before moving on. She had no time to waste, and Ronald could wait until backup arrived.

"Kings, I command you to part," She ordered the chess set, which had re-assembled itself once the match had been completed. The pieces, being built by her and set to recognize her magic, quickly opened a path for her to continue through.

She found a much more welcoming sight in the next room; at least Miss Granger was alive. Hysteric and sobbing - but alive.

"Professor! Thank goodness, I-I have no idea what to do, H-Harry w-went in and I had to stay behind and he could be dead and I tried to help but I can't and you need to fi-"

If it wasn't such a serious occasion, Minerva may have given in and giggled at the girl's rapid-fire speech. Instead, she merely silenced her with a look and did her best to sound comforting.

"Now, Miss Granger, it's alright. I'm going to go and make sure Mr Potter is okay, and Flitwick should be on route right behind me. If you would like to help, just wait here and calm down, and explain the situation as quickly as possible to Flitwick when he arrives," It was valuable time she was using up here, but it had to be done.

Leaving Hermione nodding meekly, she strode towards the flame. With a contemptuous flick of her wand, she dispelled the flames, and a couple cooling charms saw her continuing through the now-dark fireplace with ease.

"How touching…" She could hear a strange voice hissing as she entered. "I always value bravery… Yes, boy, your parents were brave… I killed your father first and he put up a courageous fight… But your mother needn't have died… She was trying to protect you… Now give me the Stone, unless you want her to have died in vain."

In an instant, she took in the scene and reacted. Quirrell, standing over Harry. Quirrell, with his turban removed and an odd lump on the back of his head. An odd lump which appeared to be moving. Harry was clearly attempting to get away, and had blood coated his forehead. There was only one way she COULD react.

"Get away from him, ye coward!" The Scottish witch yelled, her anger causing her accent to appear in full force. In an instant, her wand was up and flashing, sending a barrage of curses at the monstrosity in front of her.

In one smooth movement of her wand, as Quirrell attempted to protect himself from the oncoming curses, she summoned Harry to her. Placing him behind her, his limp body putting up no resistance, she spared a moment for a quick diagnosis charm to check his vitals.

Though it supplied her with the knowledge that he had merely passed out, it nearly cost her her life. The brief distraction was all Quirrell needed to send back his own curses, far darker than the ones she had used. It was nothing but a hastily erected shield and a healthy dose of luck that none of the first wave of spells connected, one blazing right by her face.

Resolving herself to protect her brave Gryffindor at all costs, McGonagall gritted her teeth and sent the most powerful Reducto she could at the creature in front of her, using the dust it provided to cast a flurry of transfigurations on the rocks around her feet.

By the time Quirrell could see clearly once more, there was several suits of armour, a bear, and a bobcat already rushing towards him.

"Is that all you've got? You're not as quick as you used to be, Professor. Then again, transfiguration has always been such a weakling's branch of magic. James was one of your favourite students, wasn't he? And yet, I killed him with ease. Pathetic."

Minerva watched the rogue professor blast apart her transfigurations while seemingly effortlessly talking, except it appeared that his mouth wasn't moving… And why was he claiming to have killed James Potter? 'Unless…'

"I-impossible. You're not You-Know-Who… You can't be."

"Can't I? Quirrell, turn around," The voice hissed, once again without Quirrell moving her lips. As he turned, her worst fears were realized when she caught a glimpse of the grotesque thing on the back of Quirrell's head.

Her moment of shock was mirrored on Voldemort's face, however, when she quickly recovered and conjured a flock of birds which flew at him, rapidly pecking at any bit of exposed skin they could find.

"ENOUGH!" Quirrell and Voldemort screamed it simultaneously, as a blast of magic radiated outwards from him and instantly destroyed all of her conjured birds.

The shockwave radiating outwards from him was enough to knock her off her feet and send her tumbling to the floor, where she was stuck fumbling for her wand.

"I'm done playing games… I'm tired of your interference…" The Dark Lord hissed, his voice shaking with rage. "AVADA KEDAVRA!"

As the jet of green light headed for McGonagall, who had gotten to a crouched position protecting Harry with her body, she closed her eyes. She'd had a good run. Hopefully the Dark Lord would be too busy gloating over her corpse to kill Harry and Filius would have a chance to arrive, hopefully with backup. She'd gotten rusty over the years of peace, and she cursed herself for not noticing.

However, the expected green glow never filled her eyes, and she hesitantly opened them, to see Quirrell blasted across the room, spinning head over heels before slamming into a wall.

The cavalry had arrived, in the form of a certain diminutive charms professor and, hot on his heels, Albus Dumbledore himself.

She pushed herself to her feet with a small groan, ignoring the protests of her muscles. A sharp movement from Quirrell had her raising her wand, but it was in vain. The instant Quirrell trying to blast off a curse, he was hit with several more, the first one hitting him back against the wall, the second disarming him, the third tying him neatly.

Even one as narcissistic as Voldemort could see when his chance was over.

"You can't stop me. Enjoy what time you have left," With that last parting message, the Dark Lord abandoned his host body. A dark shadow rose from it, which was instantly disappeared.

The three professors watched the scene impassively. Several tense moments passed before Dumbledore finally clapped his hands.

"Let's get young Harry here to the hospital wing. He seems to have had a long night, and I'm sure an explanation of what exactly happened here can wait until he's rested a bit," The wise old wizard said sternly, before breaking into a gentle smile. "Well done Minerva. Are you alright?"

"I-I'm fine, just a little shaken. He was in the castle all along…" Even now, she could hardly believe it. They'd allowed him in a classroom with children, alone. It was an unacceptable breach of the school.

"Where would you think his shade will go, Albus?" Filius squeaked, his voice an octave higher than usual.

Dumbledore paused, deep in thought. "The wards will see to it that he is forced out of the school grounds. Past that, I'm not sure. He's likely off looking for another host body, wherever he can find one."

With a drawn-out sigh, the headmaster broke into a gentle smile. "Now, Minerva, Filius, how about we retire to my office for some tea and lemon drops? Minerva, you can explain to me anything I may have missed, and rest a bit."

A/N: Hope you all enjoyed! My take on how the story might have changed had McGonagall not blown off Harry & Co. when they came to her for help. Just a one-shot for now, but interesting how the story would change as a result. Flamel, his stone still being in one piece, could have survived and joined the war effort, or at least assisted in Harry's training. McGonagall would have been paranoid about new teachers and could possibly completely change the DADA professors being brought into the school.

The butterfly effect could lead to quite a few changes in the Potterverse, with this one change.

Thanks for reading!

A/N2: Edited it a little bit, changed up the wording in places and tightened up some of the grammar. Still some room for improvement, but I'm happy with what I've got. Thanks again for reading! Don't forget to drop a review! Constructive criticism is very welcome :)