Thor started it. Being busy as the king of New Asgard, he couldn't be around the Avengers Tower anymore. So he sent his brother.
"Loki has learned to behave. I promise he will be useful in your adventures, my friends."
Tony saw Stephen throw the dignified version of a temper tantrum. Rational protests. Reminder of past warnings. Thor was unmoved.
"I promise you that he is a changed man. I will personally take care of whatever problems arise from his presence."
Loki himself had not been aware of this arrangement beforehand, so he looked as uncomfortable as everyone else. Bonus points to Thor for messing around with the god of mischief. In order to deal the finishing blow, Tony said
"So I guess he can take your old room."
"Of course. Thank you, Tony."
Then he bifrosted away, leaving Loki with the Avengers. The prince got his bearings quickly, unfazed by the death and mauling threats (and portals, though there was an inside joke there Tony didn't get).
"Right. Lemme show you around."
Loki was good for exactly one month, even (gasp) befriending Stephen. The two of them bonded over magic. Grudging acceptance slowly turned into more. Disdain slowly eased as Loki stopped thinking of the sorcerer as a mortal and started appreciating his knowledge of magic and earthy things. Surprisingly, it was Stephen who taught Loki about technology and the sort, only sending him to Tony for more advanced concepts.
Then the magical pranks started. Harmless things, what with 2 other sorcerers looming over his shoulder. One morning (afternoon, whatever), Tony made himself coffee. He had gone to bed late (or early) so he needed his fuel. He poured himself a cup and brought it to his lips, preparing his taste buds for...
Stephen's tea. He'd never spat anything out so quickly. A quick check confirmed that all his coffee had been distorted. Clint was just walking in with Steve (for lunch, probably) and they started laughing at the kicked puppy look Tony now sported.
Stephen joined them, quickly assessed the situation, then poured himself a cup and rolled his eyes as he brought it to his lips.
"Merlin, Loki is trying to kill me!" Tony complained.
"What?" The two had stopped laughing.
"I thought you'd mistakenly made tea," Steve stated.
"Is it poisoned?" Clint quickly asked, checking the mug.
"No. He just transformed the coffee into my tea," Stephen explained, surprisingly not murderous at the misuse of magic. "And when I touch it, it goes back to coffee." He waved his hand over the cup of coffee, turning it back into tea before he took a sip.
Tony still looked like a kicked puppy.
"Here." Stephen did something that brought the coffee back. Tony poured it into his mouth like he hadn't drunk anything in ages.
"This means war."
They all heard Loki laughing from the next room.
Thus began a prank war between Tony and Loki, occasionally recruiting other Avengers on their team. Tony glued the furniture in Loki's room to the ceiling (with Clint's help), only to later find the god sleeping upside down via magic. Loki magically hacked Friday and made her demand ridiculous things from the engineer in order to be granted entry into his lab. Tony replaced his shampoo with electric blue hair dye. Magic, once again fixed things, though, this time, Tony enlisted Stephen to deactivate the hair colour spell. Loki had to dye his hair black again. Tony locked the fridge so it would only open when Loki begged or proclaimed Tony to be the God of engineering.
Speaking of the self-proclaimed magic cop, he was rather content to let Loki pull pranks. When Tony (angrily) demanded why, Stephen pointed out that pranks were by far the most harmless thing Loki could be doing. As long as nobody got hurt (except for Tony's pride), all was fine. And Stephen generally stayed away from their thing, until Tony needed a small magical assistance, like when Stephen had cast a spell that made any cooked meat Loki touched return to life. And while the chicken leg was just a part, the small chick that spawned was straight up adorable. The betrayed look on Loki's face was 1000% better. So yeah, harmless fun.
Until Loki expanded his list of victims.
Steve was first. Loki had cast a spell on the punching bags that made them scream in pain when hit. The harder you hit, the louder they screamed and the more they sounded like children. Bucky had figured that out and refused to touch them anymore. He usually started easy, so whatever. The other Avengers more or less knew, though somehow they forgot to tell Steve. So when Captain America hit the punching bag with all his might because he didn't quite believe in starting slow and easy, the heart-breaking shriek nearly gave him a heart attack.
This time, Stephen scolded Loki, demanding that he made the pranks less traumatizing and more fun, if he had to do anything to keep himself entertained.
"I don't know, make them say perverted things for all I care!"
Loki listened. Oh boy, did he listen.
"I'm hot and ready, daddy," the coffeemaker announced Clint the next morning in his wife's voice.
Sam was laughing so hard he almost chocked.
"Please be gentle, I haven't done this in a while," the keetle told Stephen when he went to make tea. In Tony's voice. While Tony was behind him.
"I'm going to kill him," the sorcerer announced, red in the face.
"Why was it my voice?" Tony asked instead.
"Probably randomly chose an Avenger."
"Ah, no, for Clint it was his wife," Sam supplied, muching on his toast. The toaster had been quite vocal too, with a feminine voice. "And for me it was that hot waitress I got a crush on. Which means..."
The sorcerer vanished. Sam chuckled when they heard Loki scream. Tony went to make coffee, and what do you know? It had Stephen's voice.
"I'm all heated up for you, sir." And honestly? It was unfair how sexy that baritone sounded.
Now Sam was laughing at Tony's embarrassed face.
"You don't tell him," Tony threatened.
"Fine. Though you should. Isn't it kinda obvious now that he likes you back?"
Tony just hoped that Stephen hadn't killed Loki.
They didn't see the god of mischief until 30 minutes later, when he fell from the ceiling into the meeting room. Mostly because they needed him. Stephen was still emanating a dark aura, so Loki just frowned and slithered to his chair.
"Does it help if I say I didn't expect things to go that way?" he asked. The sorcerer flipped him off.
Loki fixed his hair and appearance as well as he could, then began shuffling through the briefing papers. Well, at least one Asgardian was good with paperwork. When it came to bureaucracy, Loki was better than Thor any day, though the new king was learning. Even with Loki so far away, Thor still called or made video conferences with him to get help with bureaucracy. It was kinda cute, when Tony thought about it.
So when Tony opened the projector, it was Loki's own voice that called
"Use me however you wish."
And Tony understood why Stephen had stuck Loki in whatever dimension.
The room was silent for a few moments. Tony met Sam's confused eyes, though deliberately avoided looking at Loki and Stephen.
"You will undo this spell right now," the sorcerer growled.
"You can't do it?" Steve asked.
"Not unless we know what he enchanted," Wanda supplied. And why would she care? She and Vision were a sealed deal, though Tony was glad he didn't get to hear innuendos in the android's voice. "We'd have to do them one by one."
"In my defence, it was the sorcerer who suggested this prank," Loki explained as he waved his hands, hopefully to dismiss the magic.
"I did not! You twisted my words," Stephen defended.
"Okay, everyone calm down!" Steve tried. "Loki, this is your last warning before we call Thor."
Tony suddenly had an idea. It was a bad idea, and it would require him talking to Stephen, but it was revenge.
"Can you make a spell only work for one person?" the engineer asked, bursting into the sorcerer's room. Better to just dive in headfirst than to let awkwardness fester.
"Tony, yes. So can you?" Stephen nodded slowly. "Good. Here's my take: Loki now knows who has a crush on who because of the kinky voices, but we don't know anything about him. So can you make it only work on him?"
"If you require confirmation for your feelings, there are other, more conventional ways, like talking," the sorcerer pressed in a deadpan tone. "You know, meaningful conversation."
"I got confirmation for one, but that's not what I want. I want revenge. And don't you dare tell me you don't want it, too. You looked ready to die when my voice came out of that keetle. Don't you want to make him feel that?" Stephen sighed.
"I still think there are easier ways to find out whether he returns your feelings."
"But what would the fun be in that?" Tony grinned when he saw Stephen smirk. There was a reason he got along well with Loki. Stephen played it cool, but he was just as much of a deviant as the rest of them. "And as thanks for your cooperation, I will tell you that when I used the coffeemaker, it didn't have Loki's voice. I figured that's because I have two crushes and the spell was designed for one."
Stephen shook his head and tried to stop him, standing up.
"Tony, look, you don't owe me anything..."
"It was yours. You missed it by 30 seconds." At least that made him freeze. It was a rare treat. "So, what do you say? I like you, you like me. Sounds pretty straightforward." The sorcerer chuckled and kissed him. "That's better."
"Don't forget that we both like Loki."
Tony laughed. Of course.
Of all the items Loki was around, they figured that his knives were the safest bet. Along with other household items that Loki annoyingly didn't use at all. He did everything with magic. Go figure.
After the previous prank, Wanda kept an eye out for spells as well. So it barely took her any time to figure out what Stephen had done, though she agreed to keep silent.
Tony also didn't waste any time in making his newest relationship known to the Avengers. He was rather obnoxious by nature, so Stephen became his new pillow no matter where the sorcerer was seated. The other man didn't seem to mind. The sanctum was his main home, so he wasn't around all the time anyway.
Loki, for his part, looked like a kicked puppy for whatever reason, be it their relationship or the prank ban. Maybe both. After a few days of brooding, however, Stephen dragged him to a spar, to train their magic, which was some serious bullshit, but the god bought it. Tony tagged along to watch his boyfriend.
The knives stood silent at first, which disappointed Tony, but, soon enough, Stephen activated the spell and...
"You handle us so well, daddy!" Loki froze. Of course. Each knife had a voice. One was Tony and the other Stephen. Was it revenge? It had to be. He was mortified. And they were laughing so hard... Stephen he had sort of expected, but Tony returned his feelings, right? Though he had started dating the other sorcerer and yeah, it was cruel that the two men he had crushes on were dating each other, trapping him.
Loki sheathed his knives with a grin. He had enough experience with hiding his feelings.
"Okay, lesson learned. I believe you mortals call this karma?" Stephen nodded while Tony approached the god. Loki flinched and took a step back. "The purpose of this training exercise was thus to make me use my weapons?" He returned them to their sheaths and waved his hands a bit. The smiles had vanished. Tony looked at his boyfriend, asking for help. He could tell that Loki was getting ready to flee.
"Tony wanted to see whether you felt the same for us," Stephen then said, approaching the two. "Because he's not the only one who has feelings for you."
"I see..." Loki looked at them, but didn't seem uncomfortable with the sorcerer approaching. "And now that you know?"
"We wanted to know whether you would be amenable to a relationship with us."
"You would date me?" He turned towards Tony. "The man who threw you out of a window?" Then Stephen. "The one you see as a threat to your planet?"
"You were under the influence of the mind stone," Tony replied.
"Do you believe that I see you as a threat?" Stephen asked. Loki shrugged. "Okay, fine, I did, but not anymore. I like you. We became friends before you started this stupid prank war. I was hoping we could be more, but you were so focused on Tony... So I just let you go." That had been a lot more honest than he intended.
"You still stuck me in the freefall dimension."
Now Stephen took a step back, looking guilty.
"You weren't going to listen and I was angry. You keep forcing me into a pseudo-parenting position."
"Kinky," Tony commented. The sorcerer glared at him, but Loki didn't seem as opposed to the idea, so the engineer started laughing. "Oh, we really need to talk about our kinks! So what do you say, Loki?"
"I accept, of course."
Thor came for a surprise visit a few weeks later and found the three napping on the ridiculously huge couch Tony had bought just for them, all cuddling. The king stared as Bucky passed by, completely at ease and uninterested.
"Did I miss anything?"