After 2 years of marriage, Steve and Tony finally decides to adopt. They knew they can't expect to be prepared for everything that comes with parenthood but even they are out of their depth with little Harry and his inhuman intellect. Deaged!Genius!Harry.

Chapter 1

One of the biggest advantages of being super rich and super resourceful was that when you wanted to get things done, there were always people ready to do them for you. Whether it's organizing a party or adopting a child, like in this case, Tony Stark can jump over the legalities of it all so fast that a month long process can be reduced to a matter of days. Normally Steve would be against Tony using his considerable fortune to gain favours in such a blatant manner but he was too happy that they had already found a couple that fit their adoption criteria too care much about technicalities.

"I can't believe we'll going to be parents," he repeated for what felt like the thousandth time as he and Tony made their way in a private car to where they will be meeting the couple who will be offering them their child, "It's so unreal."

"Mmm," was Tony's only response as he continued to read whatever that had caught his attention on his tablet.

"2 years ago, I woke up to find that the last 70 years have gone by without me and now I'm married, have a wonderful job and is about to start a family of my own."

"Mmm," Tony mumbled in what might be agreement. Steve rolled his eyes, already used to the billionaire's eccentricities to be offended by his obvious lack of attention.

"What on earth are you reading?"

"Oh!" Tony finally looked up, a strange expression on his face as he responded, "I was just reading the report on this family Pepper had sent me. Rereading actually; I just find it weird, that's all."

"What's weird?" Steve asked, trying not to be affected by Tony's tone.

"It's just," Tony shrugged a little, "They seemed rather well-off and all, not super rich but definitely upper-class. They only have a son so I don't know why they are giving up their second child. And also, they are definitely British citizens so why they want to go through American channels to get the kid adopted is beyond me."

"That is a little strange," Steve admitted, "But I'm sure they had their reasons. Relax Tony. We're almost here. Try not to freak the kid out? I'm sure he's more nervous then you are."

Tony smirked.

"Ah Steve, you know me so well…"

They were called the Dursleys – a perfectly normal British family from what Pepper had dug out; no arrest records, no nothing. They were as boring as they come. They had a son Dudley and the child they wanted to put on adoption was called Harry, 4 years old, with messy black hair, gorgeous green eyes and a cherubic face.

"Thank you for coming," Mr. Dursley said when Steve and Tony finally got to their meeting point. Steve saw that Harry was sitting on a chair near the older man, his feet dangling in the air. He looked up from the ground as they approached and offered them a shy smile.

Steve immediately felt his heart melt.

"Hi Harry," he greeted the little boy as he put himself on his eye level, knowing that kids hated to look up adults as they spoke, "My name is Steve. I'll be your new daddy from today on. Is that ok?"

Harry nodded but didn't speak. Steve wasn't too bothered. The kid was 4 and has plenty of time to come out of his shell.

Steve waited silently with the boy as Tony and Mr. Dursley signed the paperwork that proclaimed that Tony and Steve as the boy's new guardians and once everything was done, Mr. Dursley took his leave without even bothering to say goodbye to Harry. Steve noticed that Harry didn't even watch him go and his dislike for the other man rose another notch. Dursley must have been a terrible caregiver for Harry to be this unemotional about his departure.

"Well that's over," Tony sighed and turned his chair over so he was now facing their new son, "Hey kiddo, how are you feeling?"

"I'm ok," Harry responded, his words tinted with a light British accent, "Thanks for taking me in."

It was such a weird response from a child so young that it took Tony and Steve a few seconds to actually process that.

"Ehh…sure, no problem," Tony finally said, "Can you tell us why your uncle wants to put you on adoption?"

"Tony," Steve snapped, outraged that the man would be so direct with a kid. But luckily, Harry didn't seem to mind at all.

"Because I'm a freak," he said simply, as if he had just answered "4" to "what's two plus two". There was no anger of sadness in his tone; he sounded detached and almost resigned; Steve felt his heart break.

"Whoever told you that is an idiot," Tony retorted hotly, eyes burning with the memories of his own neglectful childhood, "You are not a freak."

"Yes I am," Harry replied, eyes wide, "Uncle says it because it's true. I know stuff I'm not supposed to know. I know stuff that no one had ever told me. I think he's scared of me."

"What kind of stuff?" Steve asked wearily, while Tony had perked up in interest.

"Anything," Harry admitted, "Ask me."

It was a strange request but Tony gladly played along.

"What is pi?"

"Tony!" Steve snapped, because even he didn't know the answer to that. How a kid barely four was supposed to know the answer was beyond him. But to his shock, and Tony's delight, Harry opened his mouth and said: "3.14159265359. Should I continue?"

"That's incredible," Tony breathed, a familiar expression making his face light up.

"No Tony," Steve interrupted before the other man could say anything else. He knows that look; it was the look Tony adopted when he was put face to face with some kind of new scientific problem waiting to be solved. No matter how smart their adoptive kid seem to be; there's no way Steve was letting his husband turn him in to an experiment.

"But Steve," Tony whined, turning to him, "One last question."

"Tony," he started in a warning tone, one he only used when Tony was being stubborn.

"Please," Tony pleaded and in front of the man's puppy dog eyes and Harry's shrug, Steve finally relented.

"Fine," he allowed, "One last question."

Beaming, Tony turned about to Harry.

"What is cold fusion?"

Harry replied automatically, without even a second of thought.

"Cold fusion is a hypothetical type of nuclear reaction that would occur at, or near, room temperature, compared with temperatures in the millions of degrees that are required for "hot" fusion. It was proposed to explain reports of anomalously high energy generation under certain specific laboratory conditions. The original experimental results which were touted as evidence for cold fusion were not replicated consistently and reliably, and there is no accepted theoretical model of cold fusion (1). However, it is said that there may be a breakthrough in the matter with the unveiling of the arc reactor, by billionaire inventor Anthony Stark in 2013."

"Oh my god," Tony gasped, delighted, "I do not know how you know that but you're like some kind of human computer."

"You don't think I'm a freak?" Harry asked, confused at Tony's reaction.

"A freak?" Tony snorted, "Kid, you are a dream come true."

Steve resisted the urge to face palm at Tony's devilish smile.

"I can't wait to bring you home and put you to work."

Steve choked.

"Put him to work!? Tony! He's four!"

TBC.

A/N:

Quoted directly from Wikipedia.

The concept of an all knowing Harry is inspired by a TV show where the main character also seem to know everything. Who gave Harry his knowledge will only be clear later on.