“It’s all English to me,” Loki says when he doesn’t understand the dense context and vocabulary people are throwing around.
Part of his punishment is making reparations to Midgard -- literally. He sits chained in a lab that belongs to S.H.I.E.L.D. or maybe Stark Industries or some hush-hush branch of the military that always knew about the supersoldiers. Nobody really knows, but now it’s theirs and they all do the really bleeding-edge science there where it’s adjacent to philosophy, theology, and magic. But this has practical applications.
Loki is honour bound (and by magic chains and rune-spelled manacles, because you can never be sure about Loki) to give them all they need: - all the knowledge, all the energy, all the explanations. And he’s good at it.
And he helps Darcy with her thesis. While all the others are getting used to using the god chained in their lab matter-of-factly, with something between condescension and total disregard (and a politeness that feels exactly like snake venom spat in your eyes, he tells her), Darcy is the one to actually say ‘Thank you’, to actually think to include him when they order take-out, or talk to him about anything apart from their job. She even brings him coffee.
“You want a döner dürüm, teriyaki chicken, or insalata caprese because that’s what they left over, sorry,” she says one day, and he stares at her. “It’s all English to me,” he says, and she laughs and hits his shoulder (she does that, too) and says, “That’s what we’ve been speaking, dummy!” because she calls the God of Lies whatever she wants.
That’s when he explains to her about the All-Tongue, and her eyes grow wide as saucers.
Seems if there are too many loan-words from other languages no speaker of the All-Tongue has heard before in the context of this language, there are glitches.
He does get his food, and then she tries all sorts of tricks with unattended video cameras to get untranslated All-Tongue (not because she’s a linguist, just because she’s fatally curious like the proverbial cat), but all she gets is the language the camera has been set to as default. She gets as far as Finnish, but that’s all not very helpful.
And then there is the day when it all breaks down. Later, they learn it has nothing to do with them at all, not with the Aesir and not with their experiments or the magic or anything at all they’re concerned with. It is an attack on the mutants, dampening all the special powers there are, annulling all magic, anything that’s not strictly in the realm of real Newton-Einstein physics, all those nice little weird shortcuts.
Darcy discovers it when she brings Loki coffee one morning. He’s asleep over the workbench, his bonds have fallen off and are lying on the floor, and he’s bright blue all over. Well, anybody else would run screaming for all the help and heroes they can get, but not Darcy. She takes out her camera phone and snaps a few pictures of cool!blue!Loki, because she can so not pass this up, and then she wakes him up and offers him the mug.
He splashes it all over the lab and screams like a girl when he sees his hands all blue, and the coffee that hits his skin hisses and freezes at once. And then he’s off that stool he’s been asleep on (Loki, like cats, will preferably sleep in the most impossible positions ever), and in a corner hiding under a table spouting panicked gibberish.
Darcy goes after him, even though her hands and arms hurt badly where the hot coffee hit her, she hunkers down in front of the table and talks to Loki, all blue and panicky under there, trying to get him out or make sense of what happened.
He stares at her, and his answers are all wild and incomprehensible. He gets so frustrated he shouts, and Darcy doesn’t find un-translated All-Tongue all that cool at all. It doesn’t even sound the smallest bit like Icelandic.
“I can’t understand you!!” she shouts back.
Red, red eyes glare at her from under the table, and she wishes she still had her camera phone on because he’s spooky and scary and lovely and hot and cool all at once.
“It’s all English to me,” he finally manages, with a heavy accent like none she’s ever heard before -- that’s apparently something he can say, without translation. But whatever she says, he shakes his head. “Coffee,” he then says. “Sorry.”
She brings him a new mug, and a blanket because all that much freezing can’t be good for you, and he wraps that thing around himself and won’t come out, huddling there with his coffee like some inter-galactic hobo.
She doesn’t understand why at all, so she crawls under the table to hug him. He tries to push her off, but she’s Darcy, and you won’t get her off that easily once she’s attached herself to you. Why do translation breaking down and turning blue merit that sort of blue-screen-of-death reaction where you huddle under a table and hide completely in a blanket? She won’t leave him alone until he at least looks at her and lets her pat his arm and touch the slightly raised dark blue markings, which she finds utterly cool in a more than literal way.
So when everybody else comes and clamours for their coffee (of course it’s the intern’s job to get it!) and they see Loki loose and blue and glowering with red eyes from inside a blanket, under a table, and out of an all-encompassing Darcy hug, they all freak out, until they realise that all magic has been turned off, and Loki is actually as harmless as a bright blue psychotic kitten.
And that’s when their phones start ringing, and it’s Fury calling Stark, and Professor Xavier calling Banner, and Thor calling Jane, desperately shouting in All-Tongue, too.
The next few days are wild, with Darcy fetching metric tons of coffee, and whatever else they want while they work, and otherwise spending her days with Loki under the table, wordlessly comforting him until he’ll consent to listen to her, and start learning English the pedestrian way.
Talking a panicked Jotun off his mental tree is incredibly hard, even if he learns fast. Loki is very clever, quite apart from his magic, in any shape, and she’s progressed to explaining about Smurfs and Nac MacFeegles when he finally consents to crawl out from under the table. Apparently, it’s the most shameful and revolting thing ever in any realm to be blue, which Darcy totally doesn’t get.
Once he finally stops panicking and looks at the measurements they have, he soon points out the magic-dampening frequency that’s piggybacking on a hacked Indian satellite system, because he knows what he’s looking for.
It takes a while to take it down, and catch whatever supervillain was trying to get one over on Xavier and friends (Darcy doesn’t really care, not with Loki still hating on himself so fiercely and hiding in the largest lab coat they have that was apparently made for the Hulk or something), but when finally the magic kicks in again and Loki can turn himself human-shaped once more (Aesir-shaped, to be precise), she snogs him soundly because she can now without freezing fast to him, and puts her foot down: no more chaining up Loki in the lab.
She’ll just take him home with her, claiming she’s going to teach him proper unmagical English. But mostly, they get distracted.
It takes months, though, until she gets Loki to turn blue again so she can take not-worksafe pictures.