Inspired by a prompt on norsekink:

Lullaby and Goodnight

Tony's first clue that something weird was going on was when he walked into the bathroom and found Loki, in pajamas, brushing his teeth.

"Jesus, what are you doing here?" he demanded.

Thor's evil little brother glanced at him, supercilious even around a mouthful of Colgate, and mumbled something.

"What?" Tony demanded, thinking that if this was what his life had turned into, he was going to start wearing his armor at all times. To bed. In the shower. Whatever.

Loki rolled his eyes, spat into the sink, and repeated himself:

"I appear to be brushing my teeth. In a moment, I intend to floss. Oral care is so important to one's overall health."

"No, I mean, what the hell are you doing in our house?" Tony clarified.

"At the moment, I am brushing my teeth," Loki repeated.

"And then what? You're going to reduce the place to a smoking ruin?" Tony heard himself ask, aware even as he said it that Loki was not a guy into whose head one should be putting ideas.

Loki frowned thoughtfully. "That had not occurred to me, but… No. I feel rather tired at the moment, so I had simply planned to go to bed."

Tony opened his mouth, and then closed it. As he had initially noted, Loki was certainly not dressed for combat: he was barefoot, wearing black-and-green (of course) plaid pajama bottoms and a long-sleeved gray t-shirt with a picture of Marvin the Martian on it. It was, actually, a great t-shirt.

"That's a great t-shirt," Tony heard himself say.

"Thank you," was the indistinct reply from Loki, who had gone back to his tooth-brushing. "EBay."

"Ah." With an effort, Tony dragged himself out of the rabbit hole he had apparently fallen into. "And where are you planning to go to bed?"

"My brother will be staying in my room," Thor announced, appearing in the doorway behind Tony and frankly scaring the crap out of him again. Bucky, the Bernese Mountain Dog, crowded into the bathroom, tail thumping against Tony's legs nearly hard enough to knock him over, and leaned on Loki, who switched his toothbrush to his other hand to pat the dog's head.

"Of course. It's a sleepover," Tony mumbled, just as his brain made a leap to the idea of grown-up sleepover and then tried to crawl out his ear to escape the mental image. They're brothers, they're brothers, Loki is wearing a Marvin the Martian t-shirt, nothing WEIRD is going to be going on, Tony tried to tell himself, ignoring the fact that having the God of Mischief sleeping over at the Avengers Mansion, perfectly innocent Marvin the Martian t-shirt or not, was about as WEIRD as anyone could possibly ask for. In a feeble attempt to inject a little belated sanity into the proceedings, Tony asked, "Thor, do you think that's a good idea?"

Thor frowned, Loki looked hurt- and Tony was perfectly aware it was a manufactured look, but it was convincing enough that he suddenly felt like a real jerk- and Bucky made one of his I-love-you noises in his throat and leaned harder on Loki. Bucky had many wonderful qualities, but a watchdog he wasn't.

"Loki has been threatened by Dr. Doom," Thor explained.

"I should imagine he's been threatened by practically everyone in existence by now," Tony pointed out.

"True, but 'everyone' has not succeeded in blowing up my lair," Loki pointed out. "Almost with me in it."

"That really would have been a shame," Tony said, with all the sincerity he could fake.

"My thoughts exactly," replied Loki, unspooling a length of dental floss. Tony, considering the floss's potential use as a garrote, took a half-step backward. Loki ignored him and went back to his oral care.

"Lacking any other refuge, my brother asked me for sanctuary, and I agreed," Thor completed the explanation, in the tone one would normally expect of a guy explaining that his brother's roof was leaking and he was staying over until the landlord got around to making repairs.

"And we're going to, what? Hand him over to SHIELD in the morning?" Tony suggested hopefully. Loki gave him the hurt look again, and Thor appeared horrified at the suggestion.

"I repeat, I have been asked for sanctuary," Thor replied stiffly. Loki, on Tony's other side, might have smirked, but it was hard to tell behind all the fingers and floss in his mouth. "I have extended it, which means a cessation of hostilities for the duration of the sanctuary."

"By him, too?" Tony demanded.

Loki batted his eyes, which should not have been as effective as it was, considering what an evil little weirdo Tony knew he was. "Naturally," Loki said, in a tone of offended innocence. Tony apparently looked skeptical, because Loki drew himself up and placed his right hand, still tethered to the left with a length of dental floss, over his heart. "On my honour," he promised.

Tony hoped he could be forgiven for not feeling terribly reassured.

~oOo~

"What do you mean, Loki's in Thor's bedroom?" Steve demanded the next morning.

"Exactly what I just said," Tony replied patiently.

"And Thor knows he's there?" Steve asked. Steve was not a stupid guy, but he was definitely having trouble with this one.

"Of course he knows he's there. He invited him," Tony snapped.

Steve suddenly looked horrified. "They're not- ?"

"No, no. Oh, God, no. Loki just doesn't have anywhere else to go," Tony replied, suppressing a shudder of his own.

Steve looked apologetic. "I'm sorry, it's not that… I mean, I know it's okay for men to… I'm updating my thinking as fast as I can, but- "

"No, it's fine, the incest thing is still considered creepy," Tony assured him.

"Oh, good," Steve said, reassured. "And I mean, I know Thor wouldn't… It's just… Loki. You never know, with Loki."

"I know," Tony agreed.

Natasha, who had been a silent and wide-eyed observer of the conversation, suddenly looked at the kitchen clock. "Isn't Thor usually up by now?"

Tony and Steve looked at the clock, at Natasha, and at each other.

"He's killed him," Tony heard himself say, and his brain continued: Ohmigod, he's tricked us into letting him into the house and now he's killed Thor and he's planning to do God knows what-

Tony grabbed one of the suitcase suits and armored up, Steve grabbed his shield and Natasha a knife, and the three of them sprinted up the stairs, down the hall, threw open the door to Thor's room to discover-

Thor, hanging halfway over the side of the bed, red-and-black blankets tangled about him-

Loki, squashed into the wall on the far side, one arm wrapped around-

Bucky, who occupied a good two-thirds of the middle of the bed, paws pressed against Thor's back just barely to the point where the God of Thunder was going to be pushed onto the floor, snuggled happily into the half-smothered God of Mischief on his other side. He lifted his head as the door opened, wagged his tail once, and then went back to sleep. Thor, snoring peacefully, didn't notice the intrusion. Loki, who didn't seem to mind that his brother had all the blankets, muttered in his sleep and moved closer to the dog.

Steve, Tony, and Natasha traded sheepish looks and quietly backed out of the room.

~oOo~

Loki, as it turned out, wasn't anything like as annoying a guest as the Avengers had reasonably expected. (Okay, they had been expecting "homicidal" rather than "annoying," but it irritated Thor to hear them say so.) He was annoying, all right, but not in the ways Tony and the others anticipated.

For one thing, he was very neat. Surprisingly neat, considering the whole Agent of Chaos thing. Apparently, ultimate evil liked to know he could lay his hand on a throwing dagger or spellbook at a moment's notice. Left reluctantly alone in the Mansion, under the watchful eye of JARVIS, Loki apparently kept his word not to cause any trouble. Instead, he went around tidying things. The Mansion had rarely been so spick-and-span. As Loki pointed out later, with an expression of offended innocence that Tony suspected was going to become very familiar to them, it was not his fault if none of the slapdash humans in the establishment could find any of their belongings after they had been put away where they belonged.

That was the first day. On the second day, he got into the liquor cabinet. The Avengers were surprised to discover that Loki could actually become drunk, although when they counted the number of empty bottles lined neatly up in the dining room, they were more surprised he had not actually become dead.

The fact JARVIS was also drunk was even harder to explain, although nobody was really surprised the next day, when it turned out that only JARVIS had a hangover.

Loki also turned out to be a withering film critic. Again, given the chaos thing, this surprised Tony, anyway, but he was quite pedantic with regard to plot and motivation, and it got a little tiresome to have him point out plot holes in movies that weren't supposed to be taken seriously in the first place.

"It's about giant robots from space that transform into cars and things!" Tony said in exasperation. "It's not supposed to make sense."

Loki sniffed. "That is simply laziness on the part of the film maker."

Tony tried him on another movie, a classic. "Okay, the motivation here is, he's a shark. Sharks eat people. End of motivation."

Loki glared. "I do not wish to watch a movie in which people pretend to be eaten by mechanical sharks."

"What," Tony countered, "you'd prefer the real thing?"

It was actually funny, in a way, to watch the wheels spinning in Loki's head as he tried to come up with the acceptable answer to that question.

"Of course not," he finally said, with obvious reluctance that Tony did not much care to think about.

"If you'd prefer to see real sharks not eating people, we can always switch to the Discovery Channel," Steve suggested, which turned out to be a great suggestion in terms of keeping Loki entertained for a couple of hours, although by the end of it Tony was ready to sell the Avengers Mansion, with its view of the Pacific Ocean, and move the whole operation to New Mexico.

He finally lost patience altogether at Loki's continual muttering that this or that movie was "entertainment suitable only for children." Considering the level of blood and guts in some of the movies Loki rejected with those words, Tony had to wonder what Asgardians considered suitable entertainment for children, and whether that was part of what was wrong with Loki.

Natasha fixed that one, though: she came home on the fourth day with an armload of Disney DVDs. "You want 'entertainment suitable for children'? You got it."

They came home on the fifth day to find JARVIS sober, everyone's possessions in their normal disarray as they were supposed to be, and Loki, still in his pajamas, curled up with Bucky on the couch, watching Robin Hood for what JARVIS wearily revealed was the fourth time. Apparently he'd had to be forcibly parted from Lilo and Stitch , when JARVIS couldn't take it anymore. The wastebasket in the TV room was full of tissues, but something made Tony refrain from asking Loki how he had enjoyed the scene where Stitch re-enacted "The Ugly Duckling."

In an effort to wean him from the Disney movies, and on the theory he was practically British anyway, Tony brought out the heavy artillery that night, in the form of Monty Python.

It wasn't the success he was hoping for, at least not at first. Not only Loki, but also Thor and Steve, sat looking at the screen with expressions of deep confusion. These intensified when Michael Palin, in pith helmet and shorts, began to dance around, to the accompaniment of sprightly music, before John Cleese, slapping him gently across the face with a small fish.

And then Palin stopped, Cleese bowed, drew a fish the size of a surfboard as if it was a sword, and smacked Palin in the head with it, knocking him, with a comical splash! into a canal half-full of water.

Loki, Steve, and Thor simultaneously howled with laughter, clutching each other with glee and demanding to see that part again. Tony obligingly ran back the DVD and they watched "The Fish-Slapping Dance" a total of seven times before the three breathlessly agreed to let the show go on.

Loki and Thor were still giggling, and still pretending to smack each other with fish, when they finally went up to bed. Bucky paraded along after them, tail wagging happily, apparently still unable to believe his luck, that one of his favourite people hadn't yet done his usual thing of vanishing abruptly.

Tony turned to Steve as the brothers and the dog disappeared down the hall.

"I need to talk to you a minute," he announced. Steve gestured to Tony to follow him, led the way into his own bedroom and shut the door.

"What?" Steve asked.

"Have you heard a peep out of Dr. Doom lately?" Tony asked. Steve hesitated, and then shook his head. "Me neither. Why would he blow up Loki's lair, and then do absolutely nothing as a followup?"

"I've been asking myself that same question," Steve admitted. "In fact, I'm starting to wonder whether Loki was telling the truth about that."

"Hard to imagine Loki telling us a fib," Tony said. "But seriously, Steve, think about it. How long has it been since he actually tried to kill us? I mean, made a serious effort?"

Steve actually had to think about it. "Since… well, before Bucky, anyway. Years."

"Yeah." Tony shook his head. "I think he might be trying to worm his way back into Thor's affections. It's the only explanation that makes sense. But why would he bother?"

Steve shrugged. "Maybe he's lonely." He looked away, and Tony realized Steve's eyes had fallen on a dilapidated stuffed mouse, a souvenir of Coney Island, that sat on his chest of drawers. Remembering how Steve had acquired the mouse, Tony said quietly,

"It's not Thor's affections, is it?"

"No," Steve said. "I think he knows he doesn't have to. I think he's trying to worm his way into ours."

Tony sighed again. "I think it's working."

~oOo~

There was no telling how long the weird-yet-strangely-not-at-all-unpleasant arrangement might have continued, if the Fantastic Four hadn't brought matters to a head by capturing Dr. Doom the following week. Interfering jerks, was Tony's first thought, when he heard the news. His second was, maybe some other convenient peril might arise that Loki might have to hide from.

And then Nick Fury really screwed things up by letting them know he was going to be paying a visit to the Avengers' Mansion, sort of in the nature of a general inspection. It wasn't like Fury, to let them know such a thing in advance, which made Tony wonder whether Fury knew that if he showed up unexpectedly he might end up finding out something he would really rather not.

Loki took it well, really, packing his belongings into whatever otherworldly portmanteau he'd arrived with and taking his leave with a flourish of sarcastic farewells. Bucky, realizing he was departing, sat mournfully at the door with his ears drooping. Loki, when he reached the door, grabbed the dog gently by the head, one hand on either side of his face, and gently rocked him back and forth.

"Until we meet again, Bucky," he said, and showed no sign of annoyance when the big dog slurped him across the face.

Thor was the last to say goodbye, looking almost as downcast as the dog did. Loki hesitated a moment-

- and then reached out, caught Thor's head in exactly the same clasp he had Bucky's, rocked it gently back and forth a couple of times, and then vanished.

Tony strongly suspected that was some sort of weird Odinson way of saying "I love you."

Two weeks later, when Loki had turned all the pigeons in Central Park into giant rocs (that strangely seemed more interested in theatrical dive-bombing and ferocious cawing than in actually carrying anybody away to devour them) Tony found himself dealing with Loki, once more wild-eyed and more than a little bit nuts, and also a malfunctioning set of blasters.

Loki looked at Tony, utterly at his mercy, and at the other Avengers rushing to the rescue but obviously not able to get there on time.

And then he grinned wildly, reached into thin air behind himself…

…and produced a fish the size of a surfboard. With which he proceeded to smack Tony across the head, knocking him with a comical splash! into a canal that hadn't been there a moment ago.

And then he vanished, just as Steve arrived on the scene to pull Tony out of the water.

"Oh yeah," Tony said, a propos of nothing in particular. "Definitely working."