Since that first meeting Loki has become a constant figure in Tony's life, even though when Tony usually sees him he's blowing shit up and throwing them in to walls.

It starts as small things like that one time Tony went up to read Allie a bed time story (yeah, he does that now) and her saying, "Oh, it's okay daddy. Loki already read me one." Then it gets to bigger things like Tony opening Allie's wardrobe to find a completely new selection of clothes ("Loki took me shopping in Paris!")

And it's not that Tony isn't glad that Loki makes Allie so happy it's just that it's pretty fucking creepy to go upstairs and find your daughter's toy dinosaurs parading around her room ("Loki charmed them.") or to find a book of Norse fairy stories on her bedside table (okay so Tony doesn't mind that so much because it's pretty funny reading about Thor being dressed up in drag) he skips the ones about Loki's children though because he Allie doesn't need to know about that.

Tony read up about them the day after Loki's first visit and he thinks he understands why Loki's so angry with the other Norse Gods. Tony can't comprehend Allie being taken away from him just because she was different. That being said Allie is a human; Loki had a horse, a wolf and a serpent but still. Even his 'normal' kids hadn't been spared. When Tony had read about what happened to Vali and Narfi his stomach had started to churn.

He hasn't told any of the other Avengers, of course. He thinks it'd be a little difficult to explain that Thor's batshit baby brother and their number one enemy babysits his daughter occasionally. He thinks Bruce knows though and Pepper suspects something but she'd never consider that Loki was Allie's secret babysitter. That's just insane, right?

He's told Allie Loki's their little secret and Tony finds it vaguely amusing because it makes Loki sound like he's the Easter Bunny or the tooth fairy (now there's an image.)

Allie's much happier now though. She smiles and laughs and runs around and lets Thor give her piggy backs and Steve teach her how to swim and Tony's even caught Allie and Natasha talking and laughing together (not that Natasha would ever admit to that and Stark, I swear to god if you tell anyone.)

But Tony can't shake the terrified feeling he gets when he's with her because oh my God I'm a Dad. He worries constantly but most often he worries about what would have happened if Loki hadn't been there. If Loki hadn't fixed her.

Tony really wants to thank Loki but the problem with that is that he only sees the trickster when they're thwarting his latest evil scheme. So for a few months the only thanks he gives Loki is shooting him at half-strength (a setting he invented just for this).

"Daddy if you want to talk to him so badly why don't you write him a letter?" Allie asks one night during their hundredth rewatch of Jurassic Park (they're at the bit where the blonde chick finds Samuel L Jackson's arm. Tony thinks he looks a lot like Fury but Allie doesn't (he's got two eyes, Daddy!).

Tony looks at her and tries to think of a reason why that wouldn't work and Bruce (who Allie talked in to joining them tonight) smirks. "Uh... I suppose I could do that."

Allie smiles, "Write them in green. Loki likes green."

Tony sits down that night and tries to write a letter. He's never been good with words where they really count; sarcasm he can do, flirting? Check. Gratitude? Nope. Never been good at it. And how are you supposed to thank someone for making your kid smile anyway?

He stares at the blank page till he literally can't keep his eyes open and scribbles a short message before he crawls in to bed and dreams about green eyes and mischievous grins.

Loki,
I'm not good at this so I just wanna say thanks for helping my kid be happy. Keep it up.
T. Stark

He groans when he reads it the next day and hands it to Allie in a sealed envelope before he can change his mind. Allie smiles when she takes it and Pepper, who's arrived to take her to school, raises an eyebrow at him.

"Father-daughter stuff, Pep." He says and Allie giggles and takes Pepper's hand.

They walk off and Tony half wants to run after them and grab the letter back but he hears Allie telling Pepper that "Pepper Potts is a stupid name." And he decides that he'd rather not be assaulted by Pepper this early in the morning so he hightails it back in to the Mansion to improve the security settings. (He's also insanely proud of Allie)

He has a convention to appear at in France that weekend and Tony's told everyone that Allie's staying with her maternal grandparents but Allie had begged him to let her spend the weekend with Loki. Normally Tony would never ever leave his daughter with a super villain but when said daughter is a secret genius and has great puppy dog eyes it's hard to say no.

He hugs her extra tight before he leaves and whispers, "You better be careful, okay?"

She rolls her eyes, "I will, daddy."

He can't concentrate on anything anyone says and Pepper does most of the talking. Halfway through it Justin Hammer decides to make a half hearted attempt on Tony's life but that's about it.

When he gets back it's late and Allie's in bed apparently Bruce had picked her up from 'Grandma's.' He tries not to picture Loki as a grandmother in his head as he heads up to Allie's room. When he opens the door Allie springs out of bed and runs at him squealing, "DADDY! Loki took me to a theme park and they had a whole ride with dinosaurs!"

When he finally gets Allie back to bed she hands him an envelope, "Loki said to give you this, daddy."

The envelope contains a note that says in elegant, curly writing 'You're welcome Stark' and photos of Allie at the theme park (mostly with dinosaurs). But there's one photo that Tony thinks Allie must have taken because she's smiling widely at the camera and beside her, looking away, smiling shyly is Loki. Obviously he doesn't look like Loki because Tony's pretty sure a super villain visiting an amusement park would be frowned upon. His hair is lighter and curled and he's wearing a leather jacket and jeans. It sort of suits him.

It goes on like this for a while; Tony will give Allie a letter thanking Loki for whatever lavishly expensive gift she's come back with (or mocking Loki if it's a particularly, ahem, manly trip, like Disneyland, Loki in Disneyland, unfortunately Allie didn't have any photos of that.) And Loki will occasionally write back. Tony tells Loki about Thor's antics and Loki pokes fun at the other super villains. It's like having a pen pal. An insane, homicidal pen pal that just so happens to babysit your kid. Tony tries not to think about that too much though.

Sometimes though he'll look at Allie and wonder why she isn't scared of Loki. He's been on TV enough destroying buildings and maiming people, she's seen the news shows, she's heard the other Avengers talking about him, she knows they fight him. She must know. But then again she's only 5.

But 5 is so big.

Sometimes he thinks she did it deliberately, made friends with the super villain just to irritate him; it's the kind of think he would have done. But then again for all her stubbornness and occasional tantrums (she is a Stark after all) Allie seems like such a sweet kid.

It's Allie's birthday when he finally sees Loki face to face (outside of Avenging, of course).
Allie's birthday was on a Sunday so of course Tony made it a whole weekend thing. Friday they went to the fanciest of fancy restaurants with Pepper and Allie pranced about in a pretty dress that Loki bought her ("from Milan, Daddy!") Neither of them really do fancy food though so while Pepper apologises to the restaurant owners Tony and Allie get fish'n'chips. Saturday Tony, Steve, Clint and Thor took her to the biggest dinosaur themed theme park Tony could find and then (for kicks) he flew her to Japan because she's started to get in to anime. Sunday morning they have a party for Allie's friends from school and Tony's vaguely disgusted that there's not even a card from Allie's mum but Allie has a great time (and so does Natasha, secretly but if Tony says that she'll beat Tony to death with his own legs).

Now they're curled up in Tony's Malibu mansion watching Jurassic Park yet again, Tony knows the words now, to all three, which is pretty sad but it's Allie's birthday and if she wants to watch a bunch of dinosaurs run rampage and eat people then who is he to say no?

They're just getting to the part where the douche bag lawyer who abandons the screaming kids gets chewed on by the T-Rex (it's Allie's favourite) when he hears the door behind them swing open. JARVIS hasn't said anything so Tony immediately leaps up, battle ready.

Allie leaps up too but she's not scared, she's excited. "LOOOOKIIIIIII!" she squeals running straight into the trickster's arms. He catches her and swings her up into a hug, laughing. It's sort of adorable in a really, really fucked up way.

"You came!" Allie cries, "I didn't think you would..."

"Of course I came! I wouldn't miss your birthday for anything, I told you that." Loki says, setting her down.

Allie smiles up at him in a way that clearly says 'Present?' and Loki grins. Tony's worried because that grin is the same one Loki uses when he's failing yet again to annihilate humanity. Loki laughs and snaps his fingers and Tony sees a green tail and for one horrified minute he's convinced Loki is giving Allie a dinosaur.

It's not though; it's a winged lizard, like on that British program Allie watches where the dinosaurs come through shiny orange thingies. Allie screeches,"OH MY GOD! It's Rex!"

The lizard cheeps and settles on Allie's shoulder and Tony clears his throat. Allie looks at him guiltily, "We can keep him right, Daddy?"

Tony wants to say no because he's pretty sure extinct lizards are on the banned pets list or something but Loki is watching him carefully and Allie's using the puppy dog eyes Steve taught her so Tony huffs. "Fine, but you better not let him escape. And you're feeding him. Wait, what do extinct lizards even eat?"

Loki shrugs and Allie giggles, "Insects probably."

There's an awkward pause and Allie turns to Tony and says, "Can Loki stay, Daddy, and watch the next two films with us?"

Loki's eyes widen a fraction and he laughs, "No, Allie, I've really got to be going-"

Tony smirks, "Oh come on, Loki. Surely you wouldn't upset my little girl on her birthday." He's not sure why he says it; the last thing he wants to do is watch movies with a guy whose hobbies include genocide but Allie loves him and Loki looks like he wants to claw Tony's face off so it's a win-win thing. Sort of.

Allie smiles and leads Loki over to the couch and Tony pours himself a drink as the Norse god mouths 'I will kill you, Stark!' Tony laughs and pours himself another scotch.

It's not until the movie ends that Tony realises he's drunk a little too much because when he stands up the world pirouettes around him. "Whoa," he says, swaying and Loki raises an eyebrow at him.

"Are you feeling okay, Stark?"

Tony's about to answer when Allie springs up from the couch where she had been dozing and says, "Next movie! Next movie!"

Loki frowns at her, "Aren't you tired, Allie?"

She yawns, "Nope."

"I think you are," Loki laughs. "Maybe you can watch the other two in the morning?"

"Oh, let her stay up," Tony slurs and Loki glares at him. "It's her birthday for chrissakes."

"Fine, one more, Allie, okay?"

Allie nods and slides off the couch to change the DVD and as the film starts Tony finds himself transfixed by Loki's hands. They're so long and perfectly formed and elegant and Loki uses them a lot when he's talking. It's when he catches himself almost drooling as Loki runs his long fingers through his dark hair that he decides he's had far too much to drink. They're just hands, Stark, he reminds himself.

But they're pretty awesome as far as hands go.

This time when the film ends Allie is snoring and Loki scoops her up. "You're not fit to carry a child," he explains.

Tony doesn't argue, "Her room is this way."

Allie's room here is smaller than the one at Avengers mansion but if possible it contains more dinosaurs. Rex perches on the headboard on her bed as Loki tucks her in a kisses her on the forehead tenderly. He turns and Tony realises that he's about to leave and Tony hasn't even thanked him yet.

"Wait, I need to talk to you," he blurts and Loki pauses. He looks at Tony for a long time before nodding and leaving the room.

"Daddy," Allie mumbles sleepily. "Why can't Loki live here forever?"

He looks at her and sighs. "You know why, baby."

When he gets back in to the living room he's slightly surprised to find Loki hovering awkwardly there. Loki looks up and Tony's suddenly got stage fright. He pours himself another drink and Loki looks like he wants to tell Tony not to but he doesn't so Tony does it anyway. He downs it one and sits down on the couch.

"You're-You're..." he says looking up at Loki. There's a world of things he wants to say but eloquence fails him so he just mumbles. "Thanks for being there for Allie. I know I suck at being a dad so you know thanks."

Loki looks slightly taken aback and he squirms slightly. "Uh...you're welcome."

Tony nods and puts his head in his hands because its times like this that the reality of his situation sets in and it's so damn big. He hears Loki sigh and feels him sit on the couch beside him. "You're not a bad father, Stark." He says quietly.

Tony snorts. "You're kidding, right? It took a super villain to even get my kid to smile. Plus there's the fact that I didn't even get involved in her life until her mom..." his throat closes a little because he still can't say it. Can't quite believe it.

Loki laughs hollowly and it sounds almost like a sob, "Your daughter is happy and alive and with you. She loves you, she knows you, you saved her. My kids..."

Tony looks up and Loki's looking determinedly at the floor, jaw clenched and Tony realises how green Loki's eyes actually are. Then he thinks that this possibly more mental than Loki babysitting Allie; he's sitting on a couch almost crying next to an also almost crying super villain. Tony's allergic to emotions so immediately he starts to think of a way out.
If this was a girl Tony would kiss her but it's not a girl it's Loki but Loki's tracing the swirly patterns in the couch with those amazing hands and hell, Tony's never worried about gender too much before. Loki's pretty much Allie's second parent by this point anyway and aren't mommies and daddies supposed to this?

Later he'll blame it on the alcohol.

He leans forwards and crashes their mouths together, fully expecting to be pushed away. He was not in any way expecting the soft noise of surprise and Loki fucking melting in to the kiss.

When he pulls away Loki looks dazed, like he's just been hit by a train or something. Tony wants to take Loki apart and he's pretty sure Loki would let him. But Loki is a bad guy and Loki is Thor's little brother and Loki is supposedly batshit and Tony's not exactly one for following the rules but this might be too far.

"You should leave." The words tumble from his lips before he can really think them through and Loki vanishes.

Life gets back to normal...well normal for them. Allie still goes off with Loki but Tony never sees him. There's a lull in super villain activity and Fury thinks they're planning something big so he wants them to all be ready but being cooped up all day with each other isn't doing much for their team bond and even Allie's getting snappy.

It's been three months since Tony's seen Loki and Allie's being such a brat he's called in Bruce as reinforcement and they're trying desperately to get her to bed.

"Daddy, no! I don't want to sleep!" she screeches for the thousandth time.

Tony's about to snap when Loki materialises by the window. He's panting and gods, he looks like shit. His usually immaculate hair is messy, his clothes are torn and rumpled, his lip is bloody and there's a dark purple bruise spreading across Loki's left cheek and eye to the bridge of his nose. His eyes are slightly glazed.

"Doom was...Doom was," he stammers, "Doom wants to kidnap Allie."

Then he crumples.