"What happens if I mix this with this?" James asks, holding up two containers.
"I'm… not entirely sure, to be honest."
"But Uncle Bruce, you know everything!" The boy looks at him with a wide grin. "Will it explode?!"
The wild excitement in his eyes should be concerning, he knows, but considering the kid is holding up milk and lemon juice that were definitely not in any danger of exploding, he figures they can table that discussion for a later time.
"I didn't say I know everything," he corrects with a small smile. "And I'm pretty sure those won't explode."
"But could they?" The small boy looks at the two liquids inquisitively. "Uncle Tony said something about infinite possibilities, and said that by that logic eventually the laundry should fold itself in the dryer, and one day Aunt Pepper should make out with Maria and Uncle Clint should spend a day without perching in high places."
"James, your Uncle Tony is a moron."
"Who's Maria? And what does make out mean?"
Bruce laughed and shook his head. "You know, that is a really good question for your mom and dad."
"Okay." There was a brief pause. "Hey Uncle Bruce, how come glue doesn't stick to its bottle?"
He reaches over the counter and ruffles James's hair. "Do you ever get tired of asking questions?" James grins in response and shake his head.
"I just want to know everything you know."
He's flattered. He really is. He knows James is a very curious young boy, and the fact that he came to him with almost all his questions warmed his heart.
When James had been born, he'd actually been scared. He was terrified of hurting him, even with the other guy safely inside. What if he dropped him? What if he held him the wrong way? This wasn't even his son and he was terrified of screwing it all up. What if, somewhere down the road, James saw him as the other guy? What if he got angry about something while James was around and tore a Hulk-sized hole through the side of the tower? The kid would be horrified, seeing his uncle as a monster. Plus it would be kind of difficult to explain to the kid what had happened. He never wanted James to see him like that, so for the first few years Bruce has remained distant.
When James had started school things changed a little bit. They didn't have to look after him 24/7 so things started settling back into a routine. He'd thought it would be a little bit easier. James would have his homework to keep him busy after school, and he'd still see him around the tower obviously. There would just be a few more excuses to stay away. But then he overheard Tony talking to James, and the boy asked him for help with his science project.
"Well, that's more of your Uncle Bruce's area of expertise," Tony had told him. "I'm more of a mechanic, so when your fist motorcycle breaks down, I'm you guy."
"But I can't ask Uncle Bruce," James whined, "so I need your help."
"Well why can't you ask him? He doesn't bite."
"He doesn't like me," James mumbled. "He never wants to spend time with me and he stays away." Guilt flooded through him. He didn't want to hurt James, but he never meant to make his own nephew think he didn't like him.
He heard Tony sigh. "Uncle Bruce definitely does not hate you, James. It's complicated. I think he's afraid."
"He's afraid of me?"
"Not of you. I think he's afraid he'll hurt you. Like I said, it's complicated and I promise that when you're older, you'll understand."
The next morning he had the rare opportunity to sleep in until 9, but when he arrived to the common kitchen that all the Avengers shared James was sitting there with the rest of the team scattered around the counters and lounging on the couches nearby.
"Snow day," Natasha said when she saw Bruce start to panic. "All the schools in the area are closed due to heavy snow." He saw Tony discreetly nudge James and the kid slowly looked up at him.
"Hey Uncle Bruce?" His voice was a lot quieter than the one he usually heard James use, and his back was hunched and his shoulders curved in as if he was trying to make himself appear smaller. "I was wondering if you could help me with something."
"Well, what do you need help with?" He asked, trying to keep his voice casual and not let James know that he'd overheard his conversation with Tony.
"There's this science fair at my school and my teacher said that I should do something for it. I was wondering if you could help me come up with some ideas." James paused briefly. "But, I mean, it's okay if you don't want to. If you're busy I understand and-"
"I'd love to help."
The pair had spent the snow day in the lab and had eventually some up with the idea of super bouncy balls. It took them a week to perfect their little project and once they were satisfied with it, they took all the failures and rejected ones and pelted them at Tony when he wasn't expecting it.
"Whatcha makin'?" James's voice draws him back out of his memory. He smiles at his nephew as the boy rises up on his tiptoes to try to see into the pot.
"I'm making homemade chicken soup. We can have it for dinner and put the leftovers in the freezer. That way if you want some another day we have it." James nods and bounces in place for a few seconds.
"What would happen if I put chicken soup in my water gun?"
"A carrot would clog it," he replies without missing a beat.
"But what if-"
He puts down the wooden spoon he had been using to stir the soup and starts tickling James. "I think we should stop plotting things that will get us murdered by your mother and father. How about that?"
"But that's no fun!" James exclaims as he tries to squirm away. The giggling child manages to escape his uncle's grasp and leaps out of his range. He grins at Bruce as if daring him to chase him.
"Go wash your hands, kid. Dinner will be done soon." He goes back to stirring the soup, unsurprised when two small hands tug at his shirt sleeve.
"You're gonna help me with my science fair project later, right?"
"Oh, no he's not," Natasha says, making them both jump. "Don't think I've forgotten about last year's mishap. If I have to get called down to the school again this year…." She trails off, leaving her threat open ended.
"But mom-"
"It was a complete accident-"
"…wasn't even really our fault-"
"We didn't know it would explode-"
"Honest, mom."
Natasha simply arches an eyebrow that sends James scampering to the bathroom to wash his hands and Bruce back to stirring the suddenly fascinating soup. They both know Bruce will help James with whatever he wants, because as much as Bruce likes not having broken bones, he loves spending time with James more.