Author's Note: In honor of Avengers: Endgame coming out next week, I thought I'd finally get around to posting my Harry Potter/Avengers fanfic that's my version of the 'fix-it' fic! Please enjoy! Also, let's all not spoil Endgame for people who can't see it opening weekend! Everyone deserves the chance to enjoy the full effect without spoilers! Also, this fic will be cross posted on A03 under the same penname!

4/27 Edit: Changed the last two Realms from Midgard and Helheim to Midgard and Niflheim

Chapter 1: On the Usage of Soul Magic

In a cupboard underneath a set of stairs in Little Whinging, Surrey, England, there lies a small ten-year-old girl fast asleep. This little girl is no ordinary girl, however. Evelyn Rosalie Potter has no idea that as she sleeps, the balance of the world is hanging by a thread; waiting for a choice she's about to make.

As it is, Evelyn knows she has to be dreaming when she finds herself inside a golden castle she's never seen before. Sticking her head out of a nearby window has her gawking at how many different towers are rising toward the sky. However, after getting over her shock, she realizes there isn't a soul to be found. Her little dream world seems entirely void of anyone else, which is odd. She thinks that, given the sheer size of the place, someone should be around, but apparently not. She wanders the halls, trying to make sense of what's happening. It's not the weirdest dream she's ever had, that still belongs to the flying motorcycle one, but she still has no idea where her mind got all this from.

It isn't until she discovers the library that she finally finds someone. A woman with braided red hair is lazily browsing through the books. For all the pomp and whatnot of this bizarre dream world, she's dressed rather casually. Pale blue denim trousers, what Evelyn thinks are black boots peeking out under from under the worn hems of said trousers, and a dark grey jacket over a possibly dark green shirt. She can only catch a glimpse of a collar, so she's not certain. The only thing on the woman that seems to fit in with the dream world are the gold metal braces on her wrists and ankles. As she turns to face her, Evelyn inhales sharply at the sight of emerald green eyes—her emerald green eyes—staring back at her.

"Hello Evelyn," the woman says softly. "Won't you take a seat?"

"Do I know you?" Evelyn asks warily. Aunt Petunia doesn't like her talking to strangers, after all. And even if this is a dream, that doesn't mean Aunt Petunia won't somehow find out that she's disobeyed and punish her regardless. Aunt Petunia's good at that. The punishing bit, at least.

"That is a very complicated question," the woman sighs, absentmindedly blowing her bangs out of her face. Evelyn vaguely remembers doing that too when Aunt Petunia had let her have long hair. Now, it has to stay short or she gets in trouble. "You don't, not at the moment, but you could. On the other hand, you already do."

"That is complicated," Evelyn agrees, her face scrunching up as she tries to make sense of the woman's bizarre statement. Adults tend to do that, she's realized. They say weird things that make them think they sound so important. She really wishes they'd just come out and say whatever it is they want to say. Makes things less complicated that way.

"You'll understand soon enough if you want," she chuckles. "I really would recommend taking a seat, though. This might take a while, given that I only have an inkling of an idea about what I need to do to finish this."

Evelyn blinks. "Finish what?" She drops down into a chair, tired of standing and taking the opportunity to sit when it's not usually offered.

The woman raises an eyebrow, and Evelyn fights off the urge to shrink back. "Given what questions you aren't asking, I'm going to assume you're ten?"

"What's being ten got to do with anything?" Evelyn asks defensively, even though she's already bracing herself for a scolding. No matter how many time Aunt Petunia seems to scold her for talking back, she just can't seem to help herself.

"When you turn eleven, your life changes," the woman states matter-of-fact, settling herself in a chair as well.

"You can't know that!" Evelyn protests, growing bolder with each time the woman doesn't scold her for talking back. It's a dangerous habit to start, but she really doesn't want to stop. And for some odd reason, she feels safe.

A wry smile tugs at the woman's lips. "I've gone by many different names and titles during my life. Those who remained of Asgard called me the Trickster's Wife, seeing as I married the God of Mischief. I was Hela's Avatar here on Midgard, earning me the title Mistress of Death. To the wizarding world I was their Savior, their Chosen One, the Girl-Who-Lived and the Woman-Who-Conquered. My friends and family, though, they knew me as Evelyn Rosalie Potter."

"You're me?" Evelyn squeaks. Okay, now she understands why she needed to sit down.

"I'm what you become if events unfold the way they're currently set up to," her future self says flatly, staring intently into the fire, "and the future, while there is much love and happiness, ends with me dying in my husband's arms as the world falls to pieces around us. Being the stubborn bastard that he is, he refused to accept that as our final end, so he gave me all of his power and strength and sent my soul back."

"Why?"

Her own eyes pin her in place, a hardness in them that terrifies her. Those eyes have seen things. "So I could change what's going to happen. If this works, then things will be different this time."

Change things? What things could she possibly want to change? How could she—

"You didn't try to save Mum and Dad," she abruptly whispers, sitting ramrod straight.

"Evelyn—"

She cuts her future self off, too swamped with sudden, indignant anger to just let this go. "You didn't try to save Mum and Dad! Why, why, why?! Anyone would've been better than the Dursleys! Even bloody drunks! They probably wouldn't've made me sleep under the stairs!"

"Enough!" The thundered word finally shuts Evelyn up, and she cringes back into her seat as her future self stands and stalks forward towards the fire. The woman's hands are clenched into fists at her side, and, the longer Evelyn watches, the more she realizes the woman is shaking. "I've forgiven a lot of things that Aunt Petunia did, but that is the one thing I never can and likely never will." She turns, fixing Evelyn with a glare. "She lied to you, to us. James and Lily Potter loved us with every fiber of their being, enough to die to keep us safe. That bitch was just jealous because she couldn't have what her sister had."

Evelyn sniffles, scrubbing at the tears rolling stubbornly down her face. "Really?" She looks beseechingly at her future self, desperately hoping and praying that she isn't lying.

"Really," the woman murmurs, her expression softening as she returns to her seat, "and I'm sorry for raising my voice. It's just an excuse, but Mum and Dad are a bit of a tender subject for me." She smiles weakly. "I think you understand at least a little."

Evelyn shrugs half-heartedly, ducking her head to hide a bit. "Just a—" She swallows around a lump in her throat. "Just a bit."

"I'll try to not raise my voice again, but I promise you I won't touch you unless I have your permission," her future self states solemnly. "And there's a reason I didn't try and save Mum and Dad. Your body couldn't've handled the strain if I'd gone back any further. I was sent back with the power of a god in my veins on top of already being a rather powerful witch."

"Magic isn't real," Evelyn parrots without conscious thought. That particular fact has been pretty much beaten into her. Anything that Uncle Vernon's dubbed 'unnatural' just isn't mentioned and therefore isn't real.

"Ah, what I wouldn't give to murder Uncle Vernon," her future self snarls, almost as if she'd heard Evelyn's thoughts. Her teeth are bared, a look of pure loathing twisting her expression into something that, surprisingly, makes Evelyn feel safe. She knows now, with every fiber of her being, that this woman would never hurt her in any way, shape, or form. "Just assume that most everything that the Dursleys have told you is a lie, and to never believe a word out of their mouths again, understand?"

"Sure…?" she returns, not sure what good that'll do for long. It's not like she'll have much a choice once she wakes up.

Her future self drags a hand down her face. "I'm sorry, but our relatives are horrid creatures that deserve to be put behind bars, at least. They'll find no rest in Death, of that I'm certain. Hela wasn't overly thrilled when I mentioned what my childhood was like in passing once."

"You can do that?" Evelyn asks incredulously, a bit baffled at the idea.

"Ah, no, we can't," the woman stresses. "Well, we'll be putting them behind bars, but it'll be legal. The few benefits of being famous." Famous? She's not famous. Famous people don't live under staircases. "Aunt Petunia and Uncle Vernon will get to spend the rest of their miserable mortal lives behind bars. After that they're Hela's problem, and seeing as we're her avatar and her father's wife, well, they've no one to blame but themselves on that front. Not to mention she actually likes us."

"Bloody hell, you're talking about Hela of Asgard, aren't you?" Evelyn yelps, it finally connecting who exactly her future self is talking about. "Goddess of Death?"

"I'd forgotten we'd poked at mythology," the woman comments blandly. "Yes, although it's Hela of Helheim, not Asgard."

"Why are you talking about a Goddess of Death liking us?" Evelyn demands near hysterically. "The gods aren't even real! They're just stories!"

"They are very much real, although the vast majority of the stories about them aren't true." Her future self chuckles, a real smile spreading across her lips. "Had a few interesting conversations about those legends."

"My head hurts," Evelyn mutters, scrubbing a hand through her cropped black hair. The mere idea of legends actually being real, on top of magic as well, is a bit too much to wrap her mind around. Even with trusting everything her future self is telling her.

The woman snorts. "We tend to do that to everyone around us. House Potter's Luck is a bit of an arse." Now she sighs, slumping in her seat, and Evelyn can actually see herself in the otherworldly woman finally. Something beyond just shared looks for all that she has black hair and her future self red. She does wonder how that happened. "In any event, I've told you who I am and why I'm here, so I suppose we're to the how."

"The how?" Evelyn repeats, immediately confused. "The how of what?"

"Our current situation," her future self says with a wry smile. "Right now, I'm just a manifestation. I have no body. Your body is well and truly yours, Evelyn, and there's nothing I can do to change that. I'm simply what your soul could become and because of that, we have the ability to merge ourselves. In a sense, we'd be going from you and I to us, but only if you wanted to."

"So I can say no?" she asks. For some reason, the thought is far more comforting that she'd expected it to be. Not that she's currently planning to say no, but just the ability to be able to is a comfort she rarely ever has, so she cherishes it.

"Yes, you'd be well within your rights to say no," the woman murmurs, gazing into the flickering flames. "My memories…aren't all pleasant, to put it politely. There are moments I'm not proud of but will stand by my decisions because I believe they were right, even with the brutality that followed. However, there are memories that I…that I love with all my being."

Evelyn swallows around a sudden lump in her throat as something occurs to her. "You…you said you were…um…married to someone?"

A ridiculously dopey smile spreads across her future self's lips. "Our husband, Loki of Asgard, loves us with his entire being."

It takes all of Evelyn's self control to keep her jaw from dropping at that particular little tidbit. Loki? She marries Loki? Now that she thinks about it, her future self had dropped a few facts that had hinted at that without outright stating so.

"Of course, we were at odds with one another when we first met," the woman continues regardless of Evelyn's completely blown mind, lips curling up into a smirk the further into her memories of Loki she devils, "and there wasn't a thing either of us could do about it. After we stopped snipping at the other, we discovered we shared many things in common." Her expression abruptly goes solemn. "Unfortunately, included was a rather similar childhood, in a manner of speaking. Both of us grew up constantly second best, for reasons we didn't find out until later in life. For us, it was our magic that made Aunt Petunia and Uncle Vernon act the way they did. For Loki?" Here her future self sighs. "Not only did he find out he was adopted, but he was a Frost Giant on top of that, the very being Asgardians went to war with centuries ago and their boogeymen in nighttime tales. Merlin was that a storm to weather."

"He loves us, though?" Evelyn whispers almost fearfully but ever hopeful. If there's just one person who loves her, surely that's not too bad of a trade off?

A softer, more content smile is offered to her this time. "When we married, he swore this oath to me. 'I take you, my heart, at the rising of the moon and the setting of the stars. To love and to honor through all that may come. Through all our lives together, in all our lives, may we be reborn that we may meet and know and love again, and remember'."

Evelyn sits in silence, letting it all sink in. Mercifully, her future self doesn't say anything more. The more she thinks about it, the clearer it becomes. There never really is a way she'd say no. Not with what's been offered. The mere possibility of having someone who loves her is just too much to pass up. And even if nothing works out the way her future self seems to be hoping it will, she'll still at least be getting a chance to try. Furthermore, Evelyn Potter's no coward, no matter what Aunt Petunia or Uncle Vernon or Dudley might think. They haven't broken her yet, and from the looks of it, never will.

Steeling herself both mentally and physically, she meets her future self's steady gaze with one of her own. "Do it."

She's gifted with a blinding smile, and only then does her future self reach out towards her. The instant they clasp hands, something sparks under her skin as a flood of power slams into her. Her magic flares out, wild and chaotic—familiar and warm—while memory after memory tumbles in front of her eyes, desperately seeking something familiar to cling to. Far, far away it finds one such thing. The quickly disintegrating marriage link between her and Loki. She grabs what strength she can and hurls her consciousness down the link before darkness can take her.

"Do you dream of them often?"

Loki Odinson, second Prince of Asgard, nearly leaps out of his skin when an unknown woman's voice suddenly addresses him in his dreams. He turns away from where he's sitting with a dream version of Sigyn and Hela in the palace gardens, as if his wife hadn't died and his daughter not banished. Neither reacts to the voice. Standing nearby, watching his family with a sadness that makes Loki feel uncomfortable, is a woman with blood red hair and striking emerald green eyes.

"Do I know you?" he inquires warily while getting to his feet. Her clothing looks like nothing he's ever seen before, but the bracers she wears on her wrists and ankles are alarmingly familiar. As is the protective magic practically pouring off them.

"That remains to be seen," she murmurs softly. "My name is Evelyn Rosalie Potter, Loki Odinson, and I am here to ask for your help." She regards him with a solemn gaze. "What do you know of Soul Magic?"

He immediately stiffens and his expression grows stone cold. "I will perform no Soul Magic for you, woman. Nothing good ever comes of it. There's always a consequence you aren't expecting or prepared to pay."

She merely scoffs and rolls her eyes. "I know that, you prat, and I'm not asking you to. Once is enough, thank you." She shudders, grimacing as though in pain. "I can attest to the fact that Soul Magic hurts like a right bitch, and I thought the death spell was painful." She mutters the last part so quietly that he almost missed it.

He narrows his eyes, even more on guard than before. Who exactly is this woman who casually mentions death spells and Soul Magic, two Arts even he's wary about deviling into? "What death spell?"

She shrugs carelessly. "The one that had been slowly eating away at my magic and body for the past week or so on top of me already dealing with a shattered right leg, a broken left wrist, multiple slash wounds to my chest and arms, possible broken or bruised ribs, and a concussion to finish it off." Loki inhales sharply, the fractional widening of his eyes the only other form of his surprise he allows himself to show. "The Convergence happened and, because the alignment of the Realms was thrown out of balance, the worlds descended into chaos. That was merely the end result for myself."

"The Convergence is not to happen for another twenty years yet," he shakily corrects her.

"Hence the Soul Magic," she smiles tiredly. "We were the last two alive after seven years of trying and failing to fix things, and I was dying in your arms. You refused to lose me, much like you had Sigyn, and so we thought to try and do it all over again." She drags a hand down her face, her entire form seeming to curl inward as she drops down to sit in the grass. "I am Hela's Avatar on Misgard, or as the Wizarding World calls it, the Master of Death. The Deathly Hallows answer to me. To top it all off, I am the Heir to House Gryffindor and House Slytherin."

"Why seek me out?" he demands, refusing to kneel in turn. Refusing to acknowledge the churning in his gut that echoes the raw, protective savagery in the magic at her wrists and ankles. He hasn't heard the names Gryffindor or Slytherin in centuries, and now this woman claims to be the heir of both Godric and Salazar. And on top of all that, she's Hela's Avatar, meaning she's collected all of Hel's artifacts on Midgard and won their alliance. She's someone his daughter's acknowledged and probably holds in high esteem.

"Since you're the one who cast the Soul Magic on me, there's a chance you may be able to regain your memories of the years that'll no longer be happening. However, like I told my former current self, there are both good and bad memories. Personally, I like to think that the good outweighs the bad, but that's just my opinion. They will greatly change how you view everyone and everything you currently know, and there'll be no going back should it actually work."

"Then why offer it?"

"You aren't the only one who's possessive of those they consider theirs, Odinson," she smirks slightly, a bit of fire returning to her eyes. "Thor often commented that we brought out both the best and worst in each other. Still, even if you choose not to regain the memories, I have every intention of winning you over again."

Loki looks at her silently, already gathering an idea of how they fit together. It alarms him how much he finds himself wanting it, what with his wife and child still right behind him. How well their magic seems to meld together, even after having just brushed his own up against hers.

"And what, exactly, do you gain by offering me this?"

She absentmindedly blows a loose strand of hair out of her face. "If you say yes, and it actually works, I have someone else who knows." She looks up at him, solemn to a degree that sets his teeth on edge. "I have lived through the collapse of seven of the Nine Realms." He just barely manages to catch the strangled noise that wants to escape his throat. Stars, she can't be serious. He doesn't even want to begin to consider what sort of catastrophe would be capable of causing that kind of chain reaction. "Asgard fell four months ago for me, taking Odin and most of the Valkyrie with it. Midgard and Niflheim were the only two remaining when we resorted to Soul Magic."

Well, he thinks faintly. That certainly explains why he used it, even disregarding their supposed relationship. "And Mother?" he asks around the lump in his throat.

"She was killed during the Convergence seven years ago."

Nothing could've prepared him for those words. He stumbles back a step, chest heaving as he fights for air. Frigga had been killed. His kind, loving mother dead for seven years.

"Loki!"

The only one who never sees him as second best, who never scoffs or sneers over the fact that he'll never be the type of warrior that Thor, Fandral, Volstagg, Hogun, or even Sif are.

"Loki!"

The who encouraged his learning of magic and sciences. Who practically taught him everything he knows about working in the shadows.

"Odinson, breathe!"

He reacts automatically, the tone sounding very much used to being obeyed and he's currently in no state of mind to even contemplate disobeying. Sweet air floods his lungs, for all that this is a dream, and his world stops physically spinning. Evelyn is on her feet, a hand reached out like she wants to touch him but she stopped herself just short of doing so.

"Who?" he snarls, heart beating out a frantic tempo against his ribs.

"The Dark Elves led by Malekith," she states flatly. "A mortal somehow managed to get the Aether trapped inside their body and Malekith took advantage of the fact that they were brought to Asgard in an attempt to retrieve it."

That can't be right. Loki distinctively remembers Odin telling him and Thor how his father, Bors, had practically destroyed Svartalfheim and the Realm's inhabitants with it.

"The Dark Elves—"

Evelyn cuts him off before he can finish his sentence. "They are very much alive, Odinson, so do not attempt to tell me my information is incorrect. Malekith is so intune with the Aether that he was woken up from wherever he's hibernating just by a mortal's touch. He then proceeded to try and suck out of the light from all the Realms after taking the Aether into his body. We're fairly certain that's where everything started going wrong."

Now it's his turn to drop to the ground. So that's what caused it all. The use of one of the Infinity Stones. Given that it was the Reality Stone, it most certainly would've been capable of tearing the Realms apart.

"Thor?" he makes himself ask while already dreading the answer.

"Fell with Vanaheim making sure as many as possible to get to safety three years ago," she murmurs, kneeling opposite him and looking off into the distance. A single tear rolls down her cheek. "You never admitted it to me, but I know you'd taken a piece of Mjolnir when it broke a year prior." He's unable to help his broken sob. "It became your sole remaining connection to your brother."

He chokes out a "How?"

She answers him without needing any further explanation. "The mortal who found the Aether? Thor had fallen in love with her, despite Odin's disapproval and discouragement. What we didn't know was that the Aether had damaged her body beyond anything either of us could heal, and Asgard was no help. They closed their doors to us for the majority of the collapse. She died in his arms about a year after coming to us. He had lost his mother, was estranged from his father and friends, and only had you as a remaining connection to everything he formerly knew. Jane Foster was the one who started him on the road to true humility, and to lose her as well?" She shrugs helplessly. "We were extremely lucky that Mjolnir took the brunt of the shitstorm that followed."

Silence falls against between them as Loki tries to take in all of what she's told him. There are probably countless more horrors she's not telling him. There's haunted look in her eyes that he doesn't want to press any further than he already has. It might hurt him to go further, but he gets this feeling that it'll break her.

"And you seek to prevent all of this from happening again?"

"Yes," she returns simply. "After dealing with a megalomaniac that's hell bent on my blood, though."

He blinks repeatedly, wondering if he actually heard her correctly. "What?"

She smiles sadly at him. "I'd explain, but I'm at my limit." Now that he actually looks at her, Loki realizes that she's starting to faintly glow. "So what say you, Loki Odinson? Do you wish to try your luck with Soul Magic or not?" She holds out a hand.

He looks at it, then at her again. "Do not expect me to simply sit around and wait for you to fix your problems," he warns while reaching out. "I will find you myself if you take too long."

He's rewarded with a surprised look just before their skin touches. Then his world erupts in pain and devastation and heartbreak thirty years in the making. He lurches forward a step and Evelyn catches him, her magic wrapping comfortingly around his own.

"I'll be quick about it," she murmurs into his ear.

"Evelyn—"

She cuts him off with a kiss, and he's helpless to refuse it. He sinks into it, so achingly familiar and wonderfully new. It's sloppy and desperate and biting. They're alive. They've got a second chance. He hauls his wife tighter to himself, relishing in the feel of her beating heart against his chest.

"I love you, Odinson," she breathes against his lips, the taste of stardust and frost heavy on his lips, "now wake up."