Author Notes: I had written the whole story in one go before putting it up as I had a few uncomplete stories. This story is set between the first two avengers movies and I watched Endgames half-way though writing this – Man that was a roller coaster of a ride.

Of course I do not own the Avengers or any marvel characters. I hope you enjoy.

The Small Avenger

Summary: While on a mission to destroy a new weapon – Bruce is turned into a six year old, with no memories of being an adult. Tony takes on the responsibly of being a temporarily guardian to the small boy while he and the other Avengers try to get Bruce back to his right age.

Chapter One

Quote: If plan A didn't work don't worry the alphabet has 25 more letters - unknown

The planning of the latest mission was proving to be a little problematic. The mission was to investigate a new and dangerous weapon. What the weapon actually did was unclear but Fury had enough information to know it had to be destroyed as soon as possible. Because they have to destroy an unknown weapon and do it safely – it was a more highly scientific mission than normal. And to do this in a safe manner they needed both Tony and Bruce to find out what kind of weapon this was and find the best way to make sure it would never been used.

This meant getting Bruce to past a fight with guns to the weapon without him turning into the Hulk. They all knew this was going to be difficult and they knew the possibility Bruce was going to transform were high. The Avengers, never had to calm the Hulk down enough to change back into Bruce mid-battle before and none of them though it would work that well.

"Maybe Stark can work this out on his own," suggested Thor getting impatient with planning these small details.

Tony shook his head at once. "I wouldn't want to risk it, from the information Fury has given us this weapon look like it used some kind of radiation and I am less knowable about them than, Bruce."

"But saying that this weapon is using advance technology that Tony, knows more about." Added Bruce fairly.

Steve sat thoughtfully for a moment. They really need more information about the building and how many men were protecting the area to make a better plan. But Steve knew that the best laid plans don't always worked. "We'll split into three groups. Natasha and I will attack one end, Tony and Thor at the other. That leaves Clint and Bruce to try and gain accessed to the building without getting noticed…" This was the most logical plan to Steve and the only one that could work.

Clint looked serious as he thought about it, "Sound like a challenge," he said truthfully.

"More like mission impossible…." corrected Bruce, he knew how this was going to end up with him turning into the Hulk. His team mates could try and plan otherwise but Bruce knew this was pushing the thin lines he and the Hulk has.

"Well, if any of you have a better plan, I'll would love to hear it." Said Steve, he paused and no one spoke so Steve carried on talking. "This is the best plan we've got…." He paused again "And if there is a code green we will deal with it… the Hulk might understand the need to change back when we need him too…"

Bruce didn't look to sure "I can't make any promises," he warns – changing back wasn't pleasant for either of them – and Hulk was harder to reason with to begin with.

"We've manged with worst plans than this," remarks Natasha fairly – after all they have worked having no plans at all before. "And we need to get ready… we waste enough talking….."

…

The plan fell apart almost at once, they were attack in the Queen Jet and with the extra threat of tanks on the ground – Bruce felt like he didn't have a choice transform himself into the Hulk. "You guys can't fight tanks…." Pointed out Bruce looking down from the air. "The Hulk can…" they all seen the video clips of the Hulk fighting tanks before.

"How are you going to get to the ground?" asked Tony concentrating driving the Queen Jet as safely as he could "What are you going to do? Jump out of the moving plane?"

"I've done it before," said Bruce truthfully – he didn't feel scared at the idea.

"That's a little unsettling…" commented Tony, in a joking manner but they was a small look of concern on his face. Out of all the Avengers Tony was probably closest to Bruce – they could understand each other and challenge each other's ideas. Tony wouldn't forget in a hurry when he found out Bruce had tried to kill himself and wondered how often that though entered Bruce's mind. Then again Tony thought about it a little bit more - that was the kind of reckless thing he would do.

"Are you sure about this?" asked Steve looking at Bruce.

"We need to stop the tanks," said Bruce simply and that was true. They didn't stand much of a change with them and they had to act as fast as they could.

Natasha nodded her head in agreement as they narrowly missed another attack. "We don't have much time, we need to attack now…." she said

Thor was already out of the plane and fighting. "Ready?" asked Steve and Bruce nodded his head without saying anything they both jumped from the plane and towards the ground.

Tony shook his head "They could have waited till I've parked…." he mumble to himself.

….

Soon Iron man, Black Widow and Hawkeye all joined the fight. As his teammates were concentrating on the battle- Tony started to fight his way into the building. The Hulk appeared beside him a few minutes later knowing he was going to be needed. Into the building there come face to face with more armed man. Hulk started to fight the oncoming attacks and was growing angrier when they started to shot at him.

"When are they going to learn?" asked Tony as the Hulk shook his head in anger after scaring the group of soldiers away. Tony enter the room holding the weapon. He step out of his Iron Man suit to have a better look. "Hulk, I really need to speck to Banner…" Hulk looked at him like he wanted to punch him "Just for a moment – big machine…no smash…" Hulk growled a little "Come on, we haven't got much time…okay, you can smash your way out when we are finish…I'll tell Banner to change back…" The Hulk huffed and started to change back down the Bruce again. "At last…" said Tony handing Bruce some spare clothes from his suit.

"You brought spare clothes?" question Bruce quickly putting them on.

"Knew you were going to change…" said Tony looking at the weapon "Get over here and make yourself useful…"

Bruce moved over to take a look. "Whoa, this is complex…." Bruce frowned looking closer

"You really need laser eye surgery…." Commented Tony

Bruce snorted a little "I don't think that would end up well….."

Bruce might have a point about that. "Dose the Hulk, have bad vision?" asked Tony suddenly "And why do you still need glasses? I mean your immune system is stronger and you can't get sick…yet you still need glasses to read…."

Bruce turn to look at Tony "Not the right time, Tony…"

"So, what do you reckon this dose?" asked Tony looking at the weapon with great interest. "I've never seen anything like this before."

Bruce was still looking at it as his brain was waking up from transporting back from the Hulk. "This weapon is not meant to kill people it's meant to alter their cells…" said Bruce looking at Tony

"What….like into a Hulk type thing?"

"It doesn't seem used Gamma radiation…" said Bruce "But it might be their goal but it might not either…. I don't want to find out what it does, something shouldn't be messed with….."

Just as they were beginning to find a safe way to destroyed the weapon, the emery come into the room with large gun. "We have to deal with them…." Said Tony and Bruce nodded his head and changed back into the Hulk. "You must go through a lot of clothes…." Mumble Tony before getting back into his suit to join in with the fight.

Joining the fight the weapon was hit and somehow turn itself on. A ray like light started to fire around the room everyone it hit disappeared in front of their eyes. Tony rushed to turn it off as the ray like light headed towards the Hulk. "Banner!" yelled Tony but the warning come too late and he was also hit, but instead of disappearing the Hulk was getting smaller and smaller until a small human child was where the Hulk once stood.

"This can't be good." Said Tony to himself "Fury isn't going to like this."