HYDRA didn't create only one magic-user while in possession of Loki's scepter. There's another, and his powers are... a little different from Wanda's. The Avengers crew breaks into a HYDRA base to rescue Tony, who was kidnapped three weeks ago. Only, he isn't the way he was when he left them to go check out the place. Instead, he's now five and a half years old. And he's absolutely terrified of Steve. The Avengers do what they can to keep little-Tony happy until they can get Strange to come take a look at him, and (hopefully) change him back to his rightful age. It's not so easy dealing with a traumatized five-year-old, though, especially one who has some major attachment issues. Toward Bucky, of all people. Throw in some HYDRA shenanigans, and it makes for an interesting time, if not the most peaceful. Older-Tony isn't going to appreciate how much little-Tony blabs, either, but it's pretty hard to tell a five-year-old to shut up when no one wants to hurt his feelings...
It’s the first thing he becomes aware of as he slowly drags himself back into consciousness; that he isn’t cold anymore. He can’t remember the last time he was really, truly warm. Not while tracking through snowy forests with a 30-pound pack on his back, or during rainy days spent crouched in muddy trenches, or strapped to that damned table in that godforsaken HYDRA hellhole. Certainly not on the train, clinging to freezing metal with numb fingers, or while falling, falling, falling, before being swallowed whole by pain, surrounded by endless, suffocating darkness.