Disclaimer: I do not own Naruto, Marvel, or am I the author of Dreaming of Sunshine. I am but a simple fanfiction author that builds off of other people ideas because I find it interesting.
Tony had never intended to take on a protégé, much less two under-aged kids. However, it seems that life just has a way of undermining your expectations and pulling you into shapes that you never thought possible; case in point, the whole Sokovia Accords debacle. He knows that bringing two minors to a fistfight with superheroes probably falls under child-abuse, but at that point over half the team had just defected under Rogers' lead and he really needed some back-up with firepower to match. So he recruited the new kids on the block who hadn't smacked away the hand of friendship, Peter and Piper Parker.
Peter Parker: young, scientific genius at 16 attending Midtown School of Science and Technology on scholarship. Suspected powers being enhanced speed, strength and durability, possible danger sense. Equipment: uses a kind of self-manufactured webbing/ superglue compound that dissolves after a couple of hours of being exposed to air, as well as home-made 'web-shooters'. Close associates: twin sister and partner, Piper Parker; uncle, Ben Parker; aunt, May Parker; best friend, Ned Leeds.
Piper Parker: scientific genius of a similar caliber as her twin brother, attending Midtown School of Science and Technology on the same scholarship. No additional powers, medical file states that she possesses an unidentified mental deficiency where she falls into a fugue state. However, this doesn't seem to hold her back in her during her escapades on the street with her brother. Equipment: same webbing and web-shooter technology as her brother; possesses a solvent for their webbing. Close associates: twin brother and partner, Peter Parker; uncle, Ben Parker; aunt, May Parker; brother's best friend, Ned Leeds; close friend, Michelle Jones.
Originally, he had only wanted to bring Peter with him to Germany, but after actually meeting the twins, at was clear that that Piper wouldn't be letting him go anywhere with Peter if she wasn't along, and Peter wouldn't be going anywhere without his sister. And the shield generator that the two of them had built from scratch from thrown-out, dumpster parts, completely mind-blowing. He wouldn't be stealing the design from them, thank-you-very-much, (he wasn't Hammer) but he'd make sure these two got it patented.
Then Germany happened, and he got to witness Piper falling into one of her 'episodes'. Well, hear her at least. He heard as she pondered mind over matter, the power of convictions and bonds between. Watched later from the security cameras as she and Peter fell in as two parts of a well-oiled machine, successfully fighting Rogers until his back-up showed up. A fight that they had no business to fighting; where Peter could have died; where Rhodey nearly did. And then after that Ross started sniffing around the twins, asking for their names, their powers, to get them registered. Vision asking who Piper was, telling him about how the Mind Stone felt drawn towards her.
Tony managed to get Ross off the kids' case. Assuring the war-monger that no, they aren't really Avengers, not Inhumans either, just very good back-up. But Vision's inquiry, that the Mind Stone, one of the most powerful artifacts in the universe, was drawn to Piper Parker. 16 years old, Piper Parker with a mental malady that no one understood. That stuck with Tony. He assigned Karen, the AI for the twins' suits, to run a full diagnostics scan on both of the twins, just to make sure the two of them were healthy. What he found didn't alleviate his concerns.
Piper let off an energy signature, one worryingly similar to Vision, the Mind Stone, and the Tesseract, and a x-ray showed a stone like Vision's suspended inside her heart. It didn't appear to be hurting her, or anyone else for that matter, but it was worrisome. He erased all the evidence afterwards, because this- this couldn't get out. If anyone like Ross, or Hydra found out Piper was carrying around a piece of rock in any way comparable to either of them in her chest- Tony could feel the blood freeze in his veins at the thought. He might not be able to protect her, her or Peter.
He gets regular updates from Karen from then out, monitoring her energy levels, concealing them from other parties, notifying him when they spike. He knows when her episodes get worse; striking multiple times a day, how under the mask her eyes glow green. How she screams the apartment complex awake with night terrors. And he can't. do. anything. because this, this isn't something he can fight. He doesn't even know what triggers them, how to make them stop. He can only wait and watch, and keep them safe.
So when he takes Peter's suit, he lets Piper keep hers, though she never uses it. Then after the whole incident with Toomes, when he invites them to join the Avengers, Piper follows her brother to go back to Queens. Though he's fairly sure she knows that the invitation hadn't been a bluff.
But then Strange, the magician, shows up, and Banner's back, bringing news that Thanos, the Mad Titan, is seeking the Infinity Stones, the aspects of Creation. That he already has two of them, has taken down the Hulk, probably killed Loki and Thor. His worst fears are brought to life. Vision, Piper, Thanos is coming for both of them, and he can't protect Vision, because he isn't here, and- Then the first of Thanos's men show up, and the twins show up, and he can only do so much. Strange notices Piper the moment she shows up, Tony knows he does. The guy carries around an Infinity Stone around his neck, a stone the very same shade of green he'd seen gleaming in Piper's eyes a year before. Thankfully their enemy does not, doesn't notice. He doesn't know that Piper is so much more than she appears to be. Even as she's having another episode, the fifth one today, rambling angrily of power, space and time, of false gods and death and destruction. So when he sends Peter back down to Earth from the alien spacecraft, the last thing he tells the kid is to protect his sister.
After he manages to send the a**hole out into space, he and Mr. Magic manage to hammer out an agreement to stop Thanos on his own turf. Because he can't turn this ship around, and frankly, Strange flashing back down to Earth in one of his magic circles sounds like a terrible idea. Better to take down Thanos now, rather than bring him down to Earth. Banner will probably find the burner phone, so Vision will get some back-up. Piper's sharp enough to know that they should tag along with Banner. They'll meet up with Steve and the rest of the now-defunct Avengers and-
Thankfully, Strange doesn't ask about Piper, and they get to their destination without incident. The same cannot be said of their arrival. First crash-landing on the planet had been on auto-pilot towards. Then they get ambushed, by a mix-matched alien group called the 'Guardians of the Galaxy', before forming an alliance of convenience. They had apparently rescued Thor from the open-space graveyard that held the last of his people. (Jesus Christ that makes Tony burn, because they hadn't heard anything from Pointbreak since he'd left after Ultron. He'd known it was going to be bad when he'd heard it from Bruce, but this was just some other level of messed up.) They had also lost a team member to Thanos when he stole the Aether, the Reality Stone, from some place called Knowhere. That Thanos had conquered and halved the population of the planet Xandar, capital of the peace-keeping Nova Corps, for the Power Stone that was under their protection.
Strange uses the Time Stone to search through all their possible futures, but according to him, the futures where Thanos will lose depend on them buying as much time as they possibly can.
Fighting Thanos was a nightmare, a nightmare that kept coming. It shouldn't be that hard to keep a guy from closing his hand, but when the guy could hit like the Hulk even without the Infinity Gauntlet... Well, you make due with what you've got. They hadn't exactly been winning, but everything went to hell the moment little miss cyborg showed up, coming with the revelation that Gamorra, their team mate, was dead, likely by Thanos's hand. 'Starlord' the Guardians' leader went ballistic, going from buying time to trying to murder to ever-living-fuck out of Thanos. The Mad Titan then breaks free and they fall like a stack of dominoes. Everyone else tries to buy as much time as they can, but Thanos stops playing around, felling meteors from Titan's atmosphere. Soon, only he and Strange are left standing. Strange tries to fight Thanos one-on-one, and then gets knocked away after his 'Eye' is revealed a fake. Then it's only Tony, then he's left impaled, waiting for Thanos to kill him.
Then Strange does something, strange. He bargains with Thanos, the Time Stone for Tony's life. In a move that Strange himself had assured him that would never happen. Thanos takes the Time Stone, and Tony sees what he hadn't before. Thanos has five Infinity Stones, five where Tony had assumed he had four. Tony is left wondering as Thanos leaves. If Thanos has 5 of the 6 Infinity Stones, with Vision's being the last...
Where does that leave Piper?