Disclaimer; I don't own this story, I am just a conduit from the collective subconscious of HP Fandom.
As the battle raged on around him, Harry Potter felt a force rising within him. It felt almost like entering a holy place, or having pins and needles throughout his body. It was as if he was acutely aware of every one of the billions of cells that made his body. He couldn't properly describe it, it was just there, growing with every passing moment. It drove him forward and inspired him to feats he never anticipated. Maybe it was fate. Maybe it was magic. Maybe it was a feeling that this was IT, the be all end all of his existence.
He walked among the dead and soon to be dead of both sides. His wand flashed and sputtered sending a rainbow of colors and shaped from it's end. His voice was a mere whisper as he incanted the spells. If he had time to think he would be horrified at what he as seeing and doing, but for now his life and the lives of countless others depended on his actions. He didn't have time to think, or look, only time to act.
It was Halloween, no surprise. Halloween never went well for Harry, but this was the absolute worst. Voldemort and his Death Eaters had laid siege to Hogwarts after razing Hogsmeade in the early morning hours. There had been no demands and no quarter offered or given. Voldemort had come to take Hogwarts and everything and everyone in it as his personal property. Everyone who even thought about the possibility of escape or rescue was to be killed as an example to the new slaves-to-be, no matter their skills or abilities. There was no bargaining, the terms were complete submission or death.
The Death Eaters not only burned Hogsmeade to the ground but set fire to the forbidden forest as well. It was still burning as Harry, the teachers, and the DA fell back to the main doors in a desperate last stand. The ministry has sent a precious few Aurors and Unspeakables when Hermione had sacrificed herself in a desperate run to the owlery. Her message got out, but she never made it back to the others. The Aurors and Unspeakables were attacking the Death Eaters from behind, but were fighting a losing battle without anything to fall back to or seek cover behind.
And then Harry saw him. Approaching the steps into the castle Voldemort hadn't even drawn his wand. He was a quiet eye in the storm of chaos. Harry stopped moving and drew the sword from his belt. Godric Gryffindor's sword flashed in the grisly twilight of the battlefield. The smoke from the fires nearly blotted out the sun, but the flames provided as twisted illumination all their own. Putting his wand away Harry looked into the eyes of his parents' killer and drew the length of his blade across his palm, covering it with his own blood.
Harry walked to one of the battlements that guarded the front doors and pushed his magic into the sword and his blood. Never letting his eyes leave his opponent's Harry walked to the other battlement, the sword and his blood burning a glowing line into the ancient stones. His friends and the forces of Light were well behind his line, fighting with a group of Death Eaters who were on the very front lines.
"So long as blood runs in my veins, you shall never cross this line, self titled "Lord Voldemort!" Go home while you still can." A crack like thunder followed Harry's words. He dodged curses as he returned to the center.
"But I am Home, Potter! I am Slytherin's Heir come to take his throne. The very stones welcome me to my rightful place." Voldemort waved his minions to a halt with a bare flicker of his hand.
"You were born in the muggle world, did you ever learn about the Crimean War?"
"What of it?"
"You've already lost.
Boldly they rode and well,
Into the jaws of Death,
Into the mouth of Hell
Rode the six hundred."
"Do you fancy this your Thin Red Line of Heroes Potter? Take it, hell I'll write your poem myself but you forgot one very important thing... They died, just like you will."
"But I will have what you always wanted but never got. Immortality. In two hundred years, you will be just a footnote in history and Professor Binns will drone your name enough to put someone to sleep rather than inspire fear. My name and this line shall stand for eternity. In the eternal words of King Leonidas, Μολών Λαβέ, come get some!"
Harry charged into the thick of the Death Eaters, directly towards Lord Voldemort, sword in one hand and wand in the other. As he literally tore through his opponents Voldemort just laughed.
"You're already exhausted and you think you've got enough left to take me?"
Harry didn't respond, he just ripped his sword out of the throat of another death eater and formed a shield to protect his flank. That curious feeling from before was really powerful by now. It wasn't painful but at the same time it felt as if any second it would explode outward from his body. He felt in a detached way a curse strike his unprotected back, destroying his dragonhide vest and flaying his back open. In a way he was grateful, the curse also propelled him just a little farther towards his objective. Harry stumbled a bit but his quidditch training helped him roll with the unexpected impact.
Harry leapt to his feet and growled a feral roar when he saw how close he was. Pushing himself to his absolute limits he sprinted forward and jumped over the last circle of Death Eaters in direct defiance of the laws of physics. His face was that of a madman hellbent on destruction, witnesses would later swear he grew wings as if he were some avenging angel as he reached the peak of his jump and began to fall, a spell on his lips. "Avad..."
"Avada Kedavra!" Voldemort struck him down with the first spell he had to cast that day. The green death rushed toward Harry who had no way to dodge his fate in mid-air.
As the fatal spell connected with Harry's chest it was as if time stood still. Somehow no matter what they may have been distracted by at the time, everyone outside the castle witnessed that spell hit. A flash of magic exploded from Voldemort as the prophecy was fulfilled. A blood red wall of magic across Harry's Line became visible for an instant before it cracked and shattered as if it were a tinted pane of glass. Harry's path was set even in death, and he came down as any object in a ballistic trajectory is bound to do.
While Volemort threw his head back and laughed at the seeming defeat of all that was good and Light, Harry completed his fall. His sword struck Voldemort in the chest and slid between his ribs, piercing his lung and heart. Voldemort's laugh was cut short. The tip of Harry's wand struck his opponent in the collarbone and caused the wand to shear along the grain. The now sharpened wand continued forward as Harry's body and momentum brought the Dark Lord to the ground. It sliced into the left side of his neck and out the right. Voldemort gasped his last breath and looked into the frozen face of his killer. Most people killed with a killing curse looked shocked or even hateful. Harry just looked determined.
When Voldemort died his followers felt immense pain from their Dark Marks as the magic that branded them to their Lord burned its way back out again. A rare few died as it was just too much for their bodies to take, more fell into comas, but most were simply knocked unconscious. The defenders rallied and summoned all the wands. Another messenger was sent to the owlery to alert the ministry. As the defenders surged forward to stun and bind anything still breathing, Ginny Weasley and Minerva McGonagall approached the fallen Hero and Villain.
They carefully retrieved the sword and both pieces of his wand. After they closed his eyes and settled his features into a more peaceful visage, the sword and wand were laid on his chest as if he were one of the kings of old. They levitated him back towards the castle and laid him carefully just before his line, in the dead center of the approach to Hogwarts. It seemed a most fitting place.
The ministry eventually arrived to take the prisoners and to take command of the dead Death Eaters. As acting Headmistress McGonagall took charge over the dead students and staff. Of the nearly seventy students and staff who rose to battle that morning, only nineteen still lived to see the sunset. They had held off and eventually defeated over four hundred Death Eaters and fighters under the Imperious Curse. All of the fallen heroes, for they were after the ministry got through handing out awards, were offered internment on Hogwarts grounds. It was almost unheard of, but for these who paid the ultimate price for their loyalty, it was offered. Not everyone accepted, some had family plots where they would be buried but the offer touched their relatives. Harry Potter was eventually buried right where McGonagall had laid him, guarding the school in his eternal slumber.
Harry found himself in a grey misty void. He heard voices approaching and his heart swelled as that tingly feeling rose to crescendo and burst. His parents, Sirius, Hermione walked out of the mist and he understood what that feeling had been all day long. Harry walked forward with a confidence and power he had rarely showed in life. He embraced Hermione and kissed her deeply, as he was too scared to do in life.
"I've finally come home." He said as he held her.