There were no survivors.
The attack happened suddenly, without any indication or warning that it was coming. The magical community barely was prepared for threats from within its own boundaries - they never had a chance against the extraterrestrial threat that was the Chitauri Empire.
Stupefy didn't work. The spell just bounced off the metal bodies of the aliens. Avada Kedavra was only slightly more effective - sure, it worked as advertised, dropping Chitauri where they stood - but when one fell ten more took its place.
The magical world lasted five hours. Harry had watched as Hogwarts was razed to the ground; defended the innocents at Diagon Alley; held the last line of defense at his own home, not even questioning when the Elder Wand had appeared in his hand, only thankful for the boost in power that allowed him to fend off the aliens for a few moments more.
He had snapped when Ginny was ripped in half.
Gripping the Elder Wand, Harry unleashed Fiendfyre, rage coursing through his veins. Harry hadn't used the spell in years - not since Voldemort - because he knew that one mistake, one lapse in concentration, and the entire world of magic would be at risk of burning.
But there wasn't a community left to burn.
That thought alone sent the flames leaping up stories in height, magical fire feeding off of his despair and anger to raze more of the countryside. Chitauri fled into the skies in an attempt to escape the destruction but the flame leapt after them, not willing to let fuel escape its grasp.
Harry sat in the eye of the blaze, the body of his wife laying next to him. He did not make any effort to control the fire. It would burn until there was nothing left to burn… and then, it would turn on him, feeding on its creator as the last course before it died.
He was okay with that.
His children died at Hogwarts. His friends died defending their families. Everyone with enough sense to apparate away got caught by some kind of barrier and died a horrible death where they stood. Chitauri ripped through innocents with terrifying efficiency, and yet they did not touch Harry.
It wasn't as if he hadn't been in situations where the Chitauri had overrun him - no, he had been at the massacre at Diagon Alley.
But the Chitauri always let him live. They didn't touch him, regardless of how many of them he killed. It was maddening.
As the blaze burned around him, he mused. It was ironic, he thought, that the man who was labelled the savior of the wizarding world was its sole survivor, and even more ironic that he was the one setting it ablaze now. Nothing would stop the blaze now, and so Harry positioned his body next to Ginny's and laid down, shutting his eyes as he prepared to be scorched.
Which is why he was slow to react when the world went purple and the flames died.
He saw the purple glow through his eyelids, and he snapped into action - grabbing the invisibility cloak from Ginny's body and covering himself completely while gripping the Elder Wand. Whatever was able to erase his Fiendfyre like that commanded some serious power - in all likelihood he was about to face the leader of the invasion.
His grip tightened on the Elder Wand. This would probably be his last stand, but he wasn't going to go down without taking whatever hellish being orchestrated the genocide of an entire race of people with him.
Slowly coming to a crouch to allow the cloak to adjust to his movement, he surveyed the area, eyes almost immediately locking onto a massive purple figure. The figure was looking around, clearly searching for someone.
'Probably me', Harry mused.
His breath caught when the titan's eyes moved to his hiding place but he was relieved as his gaze swept over where Harry was hidden. Capitalizing on the deception of his cloak, Harry slowly moved behind the monster and took a moment of survey his foe.
The titan wore golden armor and carried a massive, double-bladed sword in one hand. On the other was a golden gauntlet that held two stones - one blue and one purple. Harry keyed in on the purple stone, figuring it had something to do with the power that had caused his Fiendfyre to disappear.
Slowly reaching out with his wand, Harry hesitated for a moment before casting.
"Accio purple stone," Harry whispered and was shocked when the gem did not immediately jump from the gauntlet into his hands. Instead, the titan's arm lurched and the monster spun around shocked at the sudden attack. Harry increased the amount of power flowing through the deathstick in response, granting it access to his entire magical reserve which, despite just casting Fiendfyre was still comparatively massive.
The stone wrest itself from the gauntlet with an audible pop, and flew into Harry's hand as he shed the protection from the cloak.
Now able to see his adversary, the titan lurched forward with a mighty punch which Harry was quick to counter with a Protego shield. The barrier quaked and Harry stumbled, but the shield held, buying the time needed for the stone to reach Harry's hand.
Harry allowed himself a grim smile, thinking he had robbed the titan of his power source.
And then the pain hit him.
It felt like his body was being torn apart. Power flooded into every inch of his body and he felt like he was about to combust. Screaming, Harry willed his magic to do something - pleading with it to save him from this agony. In response, the Elder Wand flared to life, releasing a vibrant purple stream from the tip into the titan who flew back hundreds of yards.
The beam became wider and wider as more power flooded into it, until in front of Harry's outstretched arm there was a wall of purple magic. Harry didn't know what spell it was, or even if it was a spell at all, but the magic was a force of sheer destruction on a scale that even Fiendfyre could not hope to match. The countryside didn't explode, or erupt in flames - it simply was erased when it came into contact with the raw power emanating from his wand.
Harry grit his teeth. Though the vast majority of the power was being funneled through the Elder Wand, his body was still - painfully - absorbing some of the raw power from the stone. He felt his insides warp as the power altered his body, changed him in ways he couldn't describe. He screamed as the stone suddenly started outputting much more power than it already had been and his body started taking in more and more of the excess energy.
And then as quickly as it had started, it was over and Harry was left gasping for breath and the stone hummed in his hand. When he caught his breath he looked down at the gem in his left hand and he felt almost a wave of satisfaction come from it.
You are worthy, the stone seemed to project.
Harry felt invincible. Power coursed through his veins as his magic sang with might. He looked over at where the titan had been launched. He took one step…
And tendrils of stone snapped around his mouth, neck, arms and legs, spreading his body out over a slab of ground that rose up to meet his back painfully. Harry grunted through the stone gag and tightened the grip on his wand, intent on casting something to get out of this trap. In response, the rock tightened further causing Harry to wince in pain and loosen his grip on the deathstick, spell momentarily forgotten.
As Harry was trying to get his bearings on the situation he found himself in, he was suddenly spun to come face-to-face with the titan he had sent flying and a handful of henchmen. A tall, pale man (though he hardly qualified for that term) was holding up a hand and was gesturing at him, leading to Harry deducing that he was responsible for whatever telekinetic attack he found himself subjected to.
Another pale man ('creature', thought Harry) was standing protectively in front of the titan, a nasty sword gripped tightly in his hands as he glared at Harry. An equally pale woman was standing next to that man, a staff in her hand crackling with electric blue energy. A hulking brute stood behind them all, a massive hammer over its shoulder.
It brought a sense of satisfaction to Harry to see that the underlings all sported serious burns over their bodies.
"Harry Potter," The titan stepped forward before sitting on a rock. Harry leveled a glare at the titan, refusing to look away from his eyes.
Harry said something from behind his gag. The monster gestured to the telekinetic lackey and the tendril of rock retracted from his mouth.
"You monster! Those were my people!" Harry spat, and the other tendrils tightened to deadly levels, forcing a gag and cough out of Harry as the psychic growled at him.
"Insolent whelp! I will kill you for your cheek!" The ebony man spat back, but the titan raised his arm.
"You will not. His race will not go extinct." The monster said.
Harry scoffed.
"Oh, you care about us not going extinct?! Real convincing after you murdered literally everyone except me." He fired, and to his surprise the monster winced.
"I came to retrieve the stone, not eradicate your people. But your resistance was… frightening to the Chitauri, and they reacted like the savages they are." The monster admitted.
"That changes nothing." Harry replied, and the titan nodded.
"No, it does not. Yet the fact remains; I do not want to end your people. But…" Weapons were drawn and the chains binding him once again grew tight.
"I will not hesitate if you do not tell me where your people have hidden the stone." He finished, and looked up directly into Harry's eyes.
"Who are you?" Harry fired back instead of responding to the threat.
"I am Thanos."
Harry's mind was racing a mile a minute. He was sure that this Thanos was seeking another stone as powerful as the one Harry currently held, but he was sure that he had never come across an artifact powerful enough to literally tear his body apart as he held it. It dawned on him.
"The resurrection stone." It was barely a whisper but it may as well have been a scream in the silence of the field. A ghost of a smile grew on Thanos' face as he replied.
"The resurrection stone. Such a crude name for something as powerful as one of the infinite six. I come seeking the Time Stone."
"How did you know we had this Time Stone? We didn't even call it that and not many of us even knew that it existed in the first place." Harry queried.
"I received intel that the Time Stone was on this planet, guarded by the warlocks of Earth. I was told that the stone was under the protection of the champion of these warlocks, the Sorcerer Supreme." At this, Thanos looked at Harry.
"You." Thanos finished.
"Sorcerer Supreme? I have never heard that title in my life!" Harry shouted, before continuing quietly.
"Besides, I got rid of the stone ages ago."
"Where is it?" Thanos demanded, raising his gauntlet.
Harry's laugh was mirthless.
"The Forbidden Forest, which I razed not an hour ago."
Harry stopped laughing when a blue portal swallowed the entire group.
When the portal collapsed, Harry found himself in what once was a familiar clearing.
"How did you…" Harry trailed off, not expecting an answer to his question. As he expected, Thanos completely ignored him and instead ordered his underlings to find the stone.
It was the woman that eventually spoke, thrusting her hand into the scorched earth.
"Here, lord. I sensed great power coming from this location."
She pulled her hand back through the earth and in it was a familiar smooth stone. Harry paled. He did not know what the stone was truly capable of, but he suspected he was about to find out.
Thanos narrowed his eyes before he turned to Harry.
"This is the stone?" He demanded.
Harry could only nod in response.
Thanos took the stone from the woman and stared at it before smiling.
"Yes, there is immense power coming from this," Thanos agreed before setting the stone into his gauntlet.
The stone burst with incredible power, energy expelling from the hallow in a blinding wave. Harry felt the bindings restraining him loosen and he capitalized on the situation, casting bombarda on the man holding him. The ebony man was knocked out cold and the rock bindings slipped away completely, allowing Harry to stand. Thanos turned to Harry, eyes full of rage.
"A trick!" He bellowed, "I will end you, sorcerer! My mercy is at an end." Thanos brought his sword down onto Harry's head but to everyone's shock, his blow was completely stopped by an invisible barrier.
The only mark of a shield was a very familiar emblem glowing of black fire in the air.
"The Hallows… I combined them." Harry gasped, and quickly shook his head. No time for that, he had bigger problems.
Harry thrust out with the hand holding the stone, causing Thanos and his lackeys to fly back several dozen yards before crashing into the ground.
Thanos was the first to get up, and he rushed towards Harry, swinging his sword. Harry dodged out of the way and sent a Reducto into Thanos' exposed side, knocking him back a few yards.
"I will raze this earth and pluck the Time Stone from its ashes and then I will reset time and do it again and again! Your penance for this trickery is the destruction of your entire planet!"
Harry narrowed his eyes.
"Hell no."
And with that, he closed his eyes fully and channeled all the energy the powerful stone was offering him into one, massive spell. He focused on the ground in front of him, the very air surrounding the villains and just as he felt the wind from the massive broadsword come down over his head, he whispered one word.
"Portus."
Then there was silence, and Harry opened his eyes to a world that he burned down, but one that he saved.
And Harry wept.
A/N: And so begins my take on a crossover that definitely hasn't been overused lately. Regardless of how many of these stories exist, though, I couldn't get this idea out of my head and so here we are: a story that - at the time of me writing this - has no name. I'm hoping to get a unique take on this crossover and not just drop Harry into Avengers 1 or Iron Man 1 like I see so many of these stories do. Not that those stories are bad because of that - no, I have read some utterly brilliant stories on this website that start with Harry wandering into New York or Malibu at the right (wrong?) time.
I think that is about all I want to say. I hope you all enjoyed the start of this story!