It had been one of those nights (more common in Natasha's life post-Tony-Stark) where, if you didn't immediately remember what happened when you woke up, you had no chance of finding out. It had involved a hotel room, apparently, a deeply expensive looking suite, and the empty bottle of Taittinger that she stepped on as she struggled out of the couch gave her a good idea what she'd been drinking.
Oh, wait. The almost empty bottle of vodka gave her a better idea. Well, it was the good stuff too.
Some kind of furry creature had made its home in her mouth, and maybe a swarm of bees in her skull. And when she tried to press a hand to her eyes (just to dig them out of her head, so they'd stop bothering her,) she found it moved stiffly. Something to do with the painful jagged slice across the palm and the dried blood halfway up her wrist.
She cursed inventively in Russian, and the sound roused the other occupant in the suite. The bedroom door opened and out stepped a dishevelled looking god of Mischief. Loki was wearing what looked like Steve's shirt (it didn't fit him), tousled hair, a cut lip, and a handful of blood to match Natasha's. "Morning," he smiled. He sounded far too morning-chipper for Natasha to believe it. She glared weakly.
Loki was officially no longer considered an enemy of SHIELD, as of the incident in the Philippines four months back. Thor had been delighted, welcomed his brother back to the side of the angels with bone crushing hugs. Steve had just been relieved that he didn't have to be part of an Asgardian family feud anymore, and once the Cap decided to accept it, the rest of the team fell in line. Eventually, the only ones who were uncertain about the idea were Natasha and Loki. Then director Fury had made it official and Natasha wasn't allowed to have her doubts any more. She could still keep an eye on Loki though - she had never heard the word ex-villain before.
Still, four months in and the only negative effect of their association was the fact that Thor insisted on celebrating it every chance he got. And Loki always rolled his eyes, but the not-quite hidden smile only convinced Steve that they had got it right. And Tony always knew where they could go to drink until Natasha agreed.
"Are the others here?" she asked blearily.
"No, we lost track of them after Stark decided to take the good Captain to a strip club, remember?" Oh, of course Loki would remember last night, with his goddamn Asgardian constitution. Natasha decided to hate him especially hard until her hangover faded. "I don't remember much after that, though."
Oh. She could still hate him. He sniffed suspiciously at his bloodied hand. "This isn't all my blood."
"You can smell-?" Natasha cricked her neck. "Of course you can smell something like that." She held up her own hand. "Maybe we match. Please try to avoid sniffing me, though. Hey!"
Before she had even finished telling him not to, Loki grabbed her wrist and pulled it close enough to smell the blood on her hand. His eyes widened. "We do!" he said in something like horror. One of the few things Natasha could read on him, that I did not plan this, oh fuck look in his eye. "This is your blood!"
Natasha frowned at the accusing note to that, like he thought it was her fault. She yanked her wrist back out of his hand. "Well, please, let me apologise for bleeding all over you."
"That's not even the worst part, though!" Loki blinked, and Natasha could see the slightly glassy eyes that showed he wasn't as unaffected by last night as he was pretending to be. He ran his hand through his hair, and hissed as it disturbed the cut on his palm. "I bled all over you as well."
"Er..." Natasha really didn't care to be bothered by crazy priority-less alien gods when her head felt the way it did. "I forgive you?"
Loki let out a quiet, "Fuck." He sank down to sit on the couch Natasha had vacated. "Well, we're brothers now."
"Please go away," Natasha said.
"Can't." Loki was starting to laugh, the bastard. "We shared blood. I'm getting flashes of memory back - we didn't leave anything out. You and I, Natasha Romanov, are blood brothers."
Natasha sat on the couch next to him. "Go to hell," she said, with a little less heat than she would usually have managed. "I have too many boobs to be anyone's brother."
Loki laughed aloud at that. "And you think I'm the most masculine person in Asgard? No, there's no such thing as blood sisters. You know, I was just thinking I needed a new brother. The one I've got is so terrible."
The swarm of whatever they were in Natasha's skull decided to declare war on the back of her eyes, and, hey, who knew metaphorical insects were so good with pitchforks? She pressed the knuckles of both hands into her useless, treacherous eyes. "Shut up." Hardly her best banter.
Loki gave her a calculating look for a second, then stood up. There was a rattling sound, then blessed, wonderful darkness fell. It took her a second to realise that the blinds were closed, and when she cracked open her eyelids Loki was standing in front of her holding a glass of water and two pills. She glared at them until he rolled his eyes and offered her the packet instead with its pills in sealed foil pockets. She took the water on faith.
He settled himself back on the couch next to her, and observed her with his chin on his hands. "You will not tell Thor," he said firmly.
Natasha glared, struggling with the foil packaging on the painkillers. "I'll do worse than tattle to your brother if you keep trying to tell me what to do."
Loki flicked a hand. "That's fair. But still, don't tell him." Natasha swallowed the pills, and half the glass in one pull. She inclined her head, fine, I won't tell him, and Loki grinned. "Excellent. Staying quiet about ridiculous things like this is what blood brothers are for."
While the cut on her hand healed, Natasha made an effort to forget the night she had done it. Well, she'd already forgotten the night... she made an effort to forget the morning after. That wasn't nearly as easy. The cut had been deep, and it was so stiff and raw for days that she started to wonder if Frost Giant blood was somehow poisonous to humans. She couldn't afford to lose dexterity to an infection.
Loki sent her a jar of salve with a note that said it would bring down the swelling. Natasha ignored it for three hours of fumbling with her pen, then tried it. Whatever was in that stuff, it was clearly more magic than medicine - the swelling was noticeably less awful in an hour, and by the next day she was almost entirely back to normal. Except for the shiny red line across her palm that was going to scar, and the fact that she'd just accepted a gift from her brand new godly blood brother.
Little things like that.
It was hard enough living half the week in the Avengers mansion with only male housemates - the bathrooms were never (never) clean, and Stark had some weird compulsion to dismantle the kitchen appliances for spare parts and then never fix them - but Natasha did not appreciate the criminal element reminding her that she was the only female Avenger.
No one got away for long with thinking she was a harmless little superheroine, but being five-and-a-half feet of death in black leather wasn't enough. There were far too many criminals who thought the middle of a fight was the best time to proposition her, and the kind of criminal who liked to shout insults over the violence always fell back on the sexual slurs for her. Being called a whore by someone whose ass she wasn't allowed to kick (what Geneva convention?) caused a rage in her that she didn't even know what to do with.
Being called a whore by some asswipe who then got away? That left her quite upset.
Natasha was sitting pretending not to fume (and snapping at Stark when he tried to ask what was wrong), when the doorbell went in the mansion. This was odd for a couple of reasons - they weren't expecting anyone, the security system hadn't warned them in advance, and they didn't actually have a doorbell - but Steve went to answer the door anyway.
Loki stood there with a faint smile and a bundle over his shoulder. The bundle groaned, and Natasha realised that was a person right before Loki lowered him to the ground in a way that was almost careful. "This is one of yours, I think."
Steve looked at the man dubiously, but Natasha already recognised him as the source of her rage. She stared. "He was one of the mortals who robbed a mortal bank earlier and slipped your net. So, here."
The hapless man struggled to his feet, his expression something like terror as his eyes met Natasha's. "Oh!" he said, "You, I- I'm so sorr--"
Loki kicked him in the back of the knee and he fell over again. "Not yet," he muttered.
"Loki!" said Thor from behind Natasha, where he'd been watching. "Does this mean you have reconsidered your decision not to join our team?"
Stark and Clint exchanged panicked looks, but Loki just smiled brightly. "Nope! Farewell Captain." He leaned around Steve. "Gentlemen. Brother."
Natasha was probably the only one who noticed he made eye contact with her instead of Thor at that last one.
He vanished from the door, leaving his prisoner behind to be arrested. Later on, at the interrogation, he stammered out a heartfelt and obviously scripted apology for the things he'd said to Natasha. Behind her back, she traced the still raw line of the healing cut across her hand.
She was smiling as she reached her apartment, coming home from her third date with a very suitable young man. Coffee, then dinner, then expensive dinner (at the kind of place he didn't need to know she could afford), and they'd exhausted all the safe topics, (wow, you like sport and hate Justin Bieber too?) and tonight had been spent finding common ground in their opinions on middle eastern politics and American foreign affairs.
There weren't many men who could keep up with Natasha talking foreign affairs, and fewer still who weren't intimidated by it, so she was treating Mark with cautious optimism.
There was an envelope waiting on her hall table. The smile only faltered a little as she saw that it was from Loki. Until she opened it up and found a thorough background check on her date. The urge to roll her eyes lasted only long enough for her to notice the list of known aliases at the top of the page. It was longer than she might have expected from a Texan IT specialist.
Real name Radek Svoboda. Well, said a weak voice at the back of her head, a man might have a perfectly good reason for changing his name. She knew that was bullshit though, and could only hang on to it until--
There it was. She had personally assassinated his uncle eight years ago.
If it had taken him eight years to plot his revenge, he wasn't the man she thought he was. She slammed the paper down on the table and ran a tired hand over her face.
Her cell phone sounded in her pocket, and she checked it out of reflex. The text was from a number she knew she had never put in her phone, but the display came up Loki anyway.
Do you want me to kill him? I could get away with it.
She shook her head and texted back, Better not to push your luck, don't you think?
Spoil my fun, why don't you, came the reply. You should call someone to comfort you, then. Rogers would come in a second. Barton would be less saccharine.
Natasha bit her lip reading that, and the alert sounded again as another text arrived. Barton would also be more likely to sleep with you if you get him drunk.
She switched off the phone, but there was a smile as she did. She wondered what it meant that the most comforting thing about this was that her blood brother had her back.
"Loki!" Steve looked alarmed to find the god of mischief wandering the halls of a SHIELD compound he hadn't been invited or allowed into. He was carrying a paper cup of coffee, and looking interestedly around him. "What are you doing here, is everything all right?"
"Fine," Loki said, all wide-eyed innocence. "Everything's fine. I only came to see my brother."
Thor looked delighted, but only for five seconds as Loki crossed the hall over to Natasha and handed her the coffee cup. "Natasha! I brought you this. So." He leaned casually against the wall next to her. "How's the super heroics?"
Automatically, Natasha twitched her hand behind her back with the incriminating still-raised welt on the palm. But Thor made a wordless noise of confusion and Loki cheerfully held up his own palm and its answering scar. Thor's jaw hung open.
"Loki! You have chosen to take a mortal as your brother? A woman?"
Loki shrugged. "I did tell her there's no such thing as blood sisters. And we were both passing-out drunk when it happened." Thor looked scandalised.
Steve looked back and forth between the two Asgardians in mounting bewilderment. He raised his eyebrows at Natasha, who reluctantly showed her own palm. "Apparently, blood brothers is a big thing on Asgard. Even if it happens when drunk." She smacked Loki in the arm with the scarred hand not currently holding coffee. "I thought you didn't want Thor to find out? You made me promise not to tell, as your blood brother."
Loki shrugged, grinning like a bastard. "I asked you not to tell him. Never said I wasn't going to tell him myself." He laughed at the look she gave him. "What? There's nothing about blood brothers that says I can't use it to mess with my actual brothers."
He scratched his chin, pretending to think. "Although... Thor's no more or less my real brother than you are. And you never dropped me off a bridge in space..."
Thor let out a horrified splutter, and Natasha rolled her eyes. "I miss being an only child," she said, but Loki's grin didn't falter even a little. "You're an asshole, and I'm going. I am, however, taking this -" she lifted the coffee cup, "- and you can apologise to him." She nodded at Thor and turned on her heel. Loki's laughter followed her down the hallway.
She maybe cracked a smile.
And so Loki became a fixture around the SHIELD facilities, including the Avengers mansion. People stopped commenting on it after they realised they couldn't actually stop him. At all. And Thor forgave him for implying that they were anything less than full blooded brothers who loved each other and spent the holidays at each other's houses.
Being as buddied up with the Avengers as he was didn't mean he was SHIELD's favourite person, though. There were plenty of people who remembered various things he had done as a villain. Plenty of people with pretty visceral reasons to remember, and Natasha couldn't blame some of them for holding grudges. Mostly, though, the problem resolved itself. Or reminded itself that Loki was a terrifying god sorcerer without any moral compunction against killing, and his big brother had a hammer that could smash cities and went away.
When people noticed the genuine effort Loki was making to not murder everyone who crossed him, though, there were a few incidents.
Natasha almost walked straight past one of them by the coffee bench in one of the great testing rooms. In the centre of the room, Stark was testing a new calibration of his flight stabilizers and Loki often came to these to observe and provide moral support. And watch Stark fall on his ass. But mostly he was there for moral support.
He was leaning back on both elbows against the bench while an agent Natasha half-recognised - Harrison, maybe? - held the coffee pot. He was holding it behind his back, which was strange, but it was the look on Loki's face that actually caught Natasha's idle gaze. The blank bored look that she'd learned was always calculated to cover some other expression. And Harrison was looking thunderous.
"That is just fascinating," Loki drawled. "Please, do tell me more."
"It's no joke," Harrison growled. "If there were any justice in the world, animals like you would be dragged out in the streets and shot. Not allowed to run around making kissy faces with superheroes. It makes me sick. You should realise that decent people don't want you around here."
Loki should have made some cutting remark then. Natasha had gotten used to his quick vicious tongue, and expected him to say something about what a just world might have in store for a face like Harrison's. Or at least a riff on the use of 'decent people'. But Loki carried on in that absent voice, "Do go on, I find what you have to say so interesting."
Natasha paused to give the coffee bench her full attention. She noticed the twitch in Loki's jaw, the barely-there tightness around his eyes, and knew just how badly Loki wanted to kill the idiot in front of him. Thinking about it, she knew that there had never really been a time in Loki's life when decent people had wanted him around. Not really.
Loki's apparent disinterest was only darkening the thunder clouds in Harrison's expression. "You're a monster. Some kind of demon, and it shouldn't be allowed," he spat. Natasha couldn't honestly say she didn't see where he was coming from. The thin white scar across her palm itched.
Not quite sure what she was thinking, she marched up behind Harrison's shoulder and whistled sharply. Harrison whirled in place and Loki glanced up, throwing her a lazy salute in greeting. She ignored him to jerk her chin at Harrison. "Hey. You know that's my brother you're talking to, don't you?"
Loki blinked, and fixed his gaze in the middle distance, but Harrison just stared. He pointed behind him at Loki, "That," he said, "Is a terrorist and a murderer. We should kill him on sight, not invite him in to drink coffee!"
Natasha pressed her lips together and nodded slowly. Her eyes dropped to the coffee pot Harrison still held. "May I?" she asked, pulling it from his hand. She set it carefully on the bench, then put her hand on the back of Harrison's neck too quick for him to react and slammed his head into the tabletop.
He made an undignified squeak, and slid groaning to the floor. A few people looked over, but Loki was apparently engrossed in watching the opposite wall and Natasha concentrated on sending out vibes of nonchalance mixed with I-could-kill-you. No one said anything.
Natasha stepped over Harrison's prone form, digging in the heel of his boot to roll him away from the coffee bench. She grabbed a paper napkin to clean her hands, and Loki nodded to her as if he'd only just noticed her there. "Nice technique," he remarked with a casual glance down. There was a smile playing on the edge of his lips, though. "I notice you missed the angle that would have broken his nose up into his brainstem and killed...?"
"Yeah, that was on purpose."
"I never miss a kill strike by accident."
The not-quite smile turned into full blown smirking, and Natasha returned a grin. "I should have known that, really."
"Yes. You should have. Coffee?" She reached for the pot and grabbed two paper cups.
"Ooh, yes, please." Loki wrapped his hands around the cup of awful, awful coffee, and suddenly the aroma from the steam changed for the better. A quick sip of Natasha's own coffee showed that Loki had transmuted that into real coffee as well. "You are my favourite brother. Don't tell Thor." Natasha rolled her eyes, but shrugged acquiescence.
Two days later, Loki told Thor.