Harry Potter X Thor, Pre-Thor, Loki is Harry's father.

"Don't move," James said, eyes narrowing as he leveled his wand at the man's heart. Or at least at where he thought his heart was. For all James knew the man kept his heart on the right side. Or maybe he had two hearts – or no heart at all.

The man glared back at him but remained where he stood. He only moved to raise his open palms up – a reluctant gesture of peace. James didn't know his name. He hadn't been told and he'd never asked. He didn't much care to know either.

The man was just as James had imagined he'd be. Tall, pale skin, ink black hair combed neatly back, and a thin, handsome face. His clothes were strange – layered fabric of green and black and a large decorative gold piece that lay over his chest. And his eyes… James' expression darkened.

"You know why I've come," the man said, his voice smooth and cultured, but with a razor edge to it. Those damned eyes of his slid past James to peak in the open doorway behind him.

James instinctively took a step forward. "You stay away from my family," James growled, his wand nearly touching the man's chest.

The man glanced down at wand and frowned. When he looked back up, James nearly flinched at the wide, inhuman smile that grew on his face. "I think we both know what is and is not 'yours'."

At that James did flinch. His hands shook as he forced back the bitter feelings of guilt and betrayal. They had put it behind them. They had moved on as husband and wife – as a family. They were happy now. James wasn't going to let this man destroy what they had struggled so hard to build.

"Harry is my son," James declared firmly.

The man raised an eyebrow and the smile on his face was mocking.

"I'm the one who stood by Lily through the pregnancy," James continued, spurred on by that smirk. "I'm the one who held him when he was born. I'm the one who rocked him to sleep when he cried. It's my name he bears! I am his father and he is my son. Not yours!"

The man's smile had disappeared, replaced now with a furious glare. "Such sentimentality is meaningless," he bit back. "The child is mine and I will not allow some worthless mortal to keep my son hostage."

James was suddenly keenly aware of just how not human this man was. He braced himself for an attack.

"James," a voice he knew and loved called gently. He winced internally. He hadn't wanted to wake Lily. He hadn't wanted her to have to see this man ever again. He looked back over his shoulder. His beautiful Lily stood just inside the door dressed only in her nightclothes. He smiled back at her reassuringly.

"Lily, it's fine. Go back to-," he started.

"Don't you tell me to go back to bed, James Potter." Lily stared him down through the threshold.

"Er," was his intelligent reply.

She stormed forward, nearly knocking James over, to glower up at the much taller man.

"What are you doing here?" Lily demanded. "I thought you'd made your opinion of mortals, and of me, clear." James swallowed back anger and jealousy. There was hurt in her voice. Hurt that shouldn't have been there. Like the man's opinion mattered. James hated him all the more.

The man hesitated, looking almost vulnerable in his uncertainty. Almost human. "I… I have not returned since…" James' eyes narrowed. "I only recently learned a child had been born." He straightened his stance and any vulnerability there might have been disappeared. "I've come to take the child to Asgard where he belongs."

"He belongs here," James argued.

"He belongs among those who can properly care for him," he countered, eyes blazing. "No human can give an Asgardian child the care and discipline he will require. He will be stronger than mortal children. In Asgard he will have others of his kind with whom he can play without fear of harming." James frowned at that. Harry had always seemed like a normal baby to him. He certainly hadn't noticed any greater strength. Maybe that was something that came later?

"And what is more, your people are at war. Humans kill each other in the streets. Not even your sorcery can protect you. Asgard is free of this. In Asgard the child would be safe." He raised an infuriating eyebrow in challenge. Daring them to argue against this point. After all, what parent didn't want their child safe?

James was frustrated by his own lack of response. But Lily shook her head, "I won't give up my son." The man's eyes narrowed.

"I won't give up my son," she repeated firmly. Determination flashing like lightning in her green eyes. "I don't care if Harry will be different from other children. I don't care that raising him will be a challenge. He's my baby and I'll do whatever it takes to give him the best life I possibly can."

James smiled and took her hand, a silent assurance that he was with her. She smiled back and squeezed his hand.

The man scoffed at them. "You honestly believe you can give him the best life possible? Do you think you can even protect him? Your war cares little for the lives of children. Even Asgardian infants are vulnerable."

"I'd give my life to protect Harry any day," Lily answered without hesitation. "If you want to take him you'll have to kill me first. And then one day you'll have to explain to him why you murdered his mother." James clenched his teeth. It was difficult to not protest the concept of Lily dying – he loved her so much. But he thought of the small helpless baby asleep in his cot. There was no denying he would do the same.

The man's gazed steeled. He seemed to be weighing her words.

"May I at least see my child?"

James was taken aback. He had given up? Was the possibility that his son might one day think him a murderer enough to make him relent? It certainly seemed that way. Or maybe… James griped his wand tight. Or maybe he really did intend to murder them. James tried to silently convey to Lily that this was a bad idea. She hesitated, glancing from her husband to the father of her child. Then, having made a decision, she nodded.

"Alright. You can see him, but if you try anything…" Lily let the warning hang, and James drew himself up to full height, ready and willing to take care of any threat.

They let him into their home. Lily led the way up to the baby room while James followed from behind keeping an eye out for any threatening moves.

Lily opened the nursery door slowly so as not to make any noise, and poked her head inside.

"He's asleep," she whispered in warning, and they the entered the room. The quiet was strange. Almost sacred in a way. Even the man didn't dare make a sound as walked toward the cot.

James couldn't help the smile that formed was he looked down at the boy sleeping peacefully on his stomach. It was an automatic reaction every time he watched Harry. He was a beautiful baby. Nearly three months old and getting bigger every day.

James must have imagined the sharp inhale he thought he'd heard the man take, because when he looked up at him his face was steely as it had been before. Then the man reached out. James tensed, but all he did was lightly brush a single finger over the back of Harry's small hand. He took Harry's hand gently in his fingers. James watched the man closely and saw the ridged expression fall into a deep frown. Slowly, he pulled his hand away.

The man looked up at the mobile hanging over Harry's cot. He watched the owl, dragon, hippogriff, and a phoenix spin in a slow circle. His hands curled into fists before relaxing.

"You have nothing to fear from me," he said, slowly. His words were soft. Not just quiet but soft. And there was something… something James couldn't quite place. "I will not return. You may raise your son in peace," and then he turned for the door.

Lily watched him with wide, surprised eyes.

"Wait," James said without really knowing what he was doing. He reached out to stop the man, grabbing him by the arm. The man turned and glared at him, but there was no real fire in his eyes. James released him.

"What- why-?" James was confused. He glanced back at the cot.

"That child belongs here." The man turned away from him, about to leave when he stopped. Green eyes, the same shade of impossible green as the sleeping baby's, locked on James. James took a step back at the sheer intensity of those eyes.

"Protect him," he said. James could do nothing but nod, and the man was gone.

His no-verbal promise would be put to the test one year later. James would die fighting. He would die fearing he had failed. His wife, too, would die that night, having refused for a second time to give up her son. But Harry, their beautiful little boy with messy black hair, bright green eyes, and the most adorable laugh, would live. And that alone was a victory.

Six year old Harry Potter fought back tears as he wiped dirt off his scrapped elbow. Dudley had pushed him over when he tried to play with the other kids and they had all laughed at him. Harry didn't like his cousin. He was big and mean and liked to hurt Harry. Harry wished he could tell Mrs. Martin what Dudley did. It was against the rules to push other kids, but he knew better than that. Getting Dudley in trouble would only make Aunt Petunia and Uncle Vernon mad at him. So he hid behind the shrubs on the far side of the playground where no one would ask what happened to his elbow.

"Excuse me, young man. Are you alright?" Harry started and spun around. A tall man in a long coat and scarf stood behind him. Harry quickly glanced around to see if maybe the man was talking to someone else, but there was no one else. The six year old couldn't help but blush. He'd never been called a 'young man' before.

"Fine, sir," Harry answered and tried to subtly cover his bleeding elbow. The man frowned causing Harry to wince. Then the man knelt down in front of him. Harry stared at his long, probably expensive, coat brush against the ground. Aunt Petunia would throw a fit if anyone ever got dirt on clothes that nice, but the man didn't seem to mind.

"That looks like it hurts," he said nodding to Harry's poorly concealed wound.

"It's nothing, sir," Harry said hurriedly. He really didn't want his teacher to find out. She would tell his aunt and uncle and they would be mad at him. The man frowned again but then he gave Harry a small smile.

"Well, it's still not a good idea to leave it untreated. Here." The man reached into his coat and pulled out a plastic water bottle. He uncapped it and motioned for Harry to hold out his arm. After a moments hesitation, Harry did so and the man poured the water over the wound. Harry tried not wince too badly when the cold water made contact. "My apologies," the man said with a sympathetic smile.

"'s ok," Harry mumbled. His face heated further. No one had ever given him so much attention before. The man gently wiping his elbow dry with a cloth from his pocket. He then covered the wound with a green bandage decorated with multicolored paw prints.

"There," the man said with a bright grin, and Harry couldn't help but smile sheepishly in return. "All better?"

Harry nodded looking at the bandage. It really helped. His elbow didn't hurt at all now.

"Thank you, sir." The man placed a hand on his shoulder causing Harry look up at him. Harry noticed the man had very green eyes.

"My name is Loki." In the distance the bell rang signaling the end of recess. Harry was too trapped by the man's eyes to notice. He smiled again, but this time it seemed somehow sad. "You'd better be going, Harry. You will miss your class."

Harry's eyes went wide and turned to run after his classmates when he realized something.

"How did you know my-". He turned around.

Loki was gone.

End.

This idea has been stuck in my head awhile now. I wrote bits and pieces of it and I'm glad I finally got the whole thing down. In case it wasn't clear here's what went down. Lily and James had a fight that ended with Lily storming off and meeting Loki during one of his trips to the other worlds. She ends up falling for him(because what woman wouldn't?) and having a one night stand. Loki basically tells her she's worthless to him and takes off. James and Lily get back together and soon find out Lily is pregnant with Loki's child. After lots of fighting they decide to stay together and raise the baby. Loki finds out about Harry and tries to take him back to Asgard, but when he touches baby Harry's hand he discovers through mysterious Asgardian ways that despite Harry being his son, he is 100% mortal.

Heartbroken from having a child that will age and die long before he will, Loki leaves and vows to forget about Harry. This proves too difficult for him and he checks in on Harry every once in a while.

I imagine that Harry's story would continue as canon through the books(minus the epilogue). I can just see Loki going to visit his son during The Avengers and drawing the attention of S.H.I.E.L.D. Thor would probably be thrilled to learn he's an uncle. Loki would no doubt be furious at them for dragging his son into everything.

Announcement! This idea has been adopted by wickedlfairy17! Read Blended Blood in HP x Avengers crossovers(links in my profile)!
Additional Announcement! AnarchicMuse has also adopted this idea. Their version is The Triumph of These Tired Eyes in HP x Avengers crossovers(links in my profile)!