Author's Note:

This is my first Avengers fic! Be prepared for a freaking-out Tony, a curious Peter, and some sappy fluff. Reviews are appreciated.

"Dad, what's that thing in your chest?"

Tony's mind goes temporarily blank. Of all the possible things his son could ask him, why did he have to ask that?

Tony sets his wrench down.

"Wh-what brought that subject up, Pete?" Tony asks, and oh my God, he can't believe he just stuttered. Tony Stark does not stutter, dammit!

"Harry's grandpa just had to get something called a pacemaker," says Peter. "He said that they actually had to put it inside his heart! And then I started wondering why you have that blue light where your heart is. So why do you have it?"

Tony Stark might be a genius, but how the fucking hell is he supposed to answer Peter's question without scaring the shit out of him? What, is he supposed to tell him that a bunch of homicidal maniacs from Afghanistan tried to kill him? Yeah, that would go down well.

And if he brought up Afghanistan, then he'd have to explain how he used to be a huge douchebag and Stark Industries used to make nuclear weapons- weapons that killedpeople- and Tony really didn't give a fuck, because he was getting a shitton of money for it.

Then there was the whole matter of him getting captured, and the cave, being bound, being tortured, and pain- so much fucking pain, and then waking up to find a car battery attached to his chest, courtesy of Yinsen. Oh God, Yinsen...

Tony really didn't want to think about that.

"Dad?" Peter asks warily. "Are you okay?"

"Go upstairs," Tony snaps.

Peter's brown eyes widen in surprise. He looks hurt.

Tony's face softens, because he really didn't mean to snap at him, and fuck, what kind of dad yells at his kid for no reason? It wasn't his fault that he brought up a touchy subject, because he didn't know that it was.

"Peter," Tony sighs, his tone considerably gentler, "please, just go upstairs for a bit, okay? I...I can't answer that question right now."

"Okay," Peter says softly. He turns, and Tony watches as he clambers up the steps from the lab.

And because Tony has no fucking idea what to do now, he throws himself back into his work, crawling underneath his Maserati once more.

"Tony?" comes Steve's soft voice. "You've been down here for hours. You need to take a break and eat something."

Sighing, Tony emerges from under the car. He really doesn't feel like eating, but he knows that Steve will probably end up forcing him out of the lab if he doesn't, which would piss him off, and he's not in the mood for an argument right now.

"Wow," Steve chuckles. "You actually listened." He takes in his husband's troubled expression. "Tony? Are you alright?"

Tony bites back the urge to roll his eyes, because no, he's not fucking alright, not since Peter brought up the arc reactor, and he just wants to go lie down and try to forget everything that he knows he'll never be able to.

"Tony?" Steve asks again, concern etched on his face.

"Peter asked me about the arc reactor," Tony mutters gruffly.

"Peter asked you about- oh. Oh, Tony…what'd you tell him?"

"I didn't. Jesus, Steve, what'd you expect, for me to just launch into the story?"

"No, of course not," Steve says, looking taken aback and a little hurt.

Tony wants to punch himself. Why is he always such an ass to the people he loves?

He walks over to his husband and puts his head against Steve's chest. "What am I supposed to tell him, Steve? I'll just end up scarring him for life."

"Peter will understand," Steve says soothingly. "He deserves to know, Tony. He's your son. I'd want to know why my father had a glowing object lodged in his chest if I were him."

"He's eight years old! He doesn't need to know what happened in the cave. Would you want to hear about how a bunch of psychotic maniacs tied up your dad?"

"No…but I think Peter needs to hear this story. The reactor is an important part of you, Tony. We knew he was going to have questions about it."

Tony sighs in frustration. He knows that every single fucking thing Steve is telling him is right, and that he was going to have to talk about it with Peter, but why did his son have to be so curious?

"Dad? Pops?" Peter calls from the top of the stairs. "There's a giant pot of sauce on the stove, but no spaghetti. Are we going to have dinner, or…?"

"We'll be up in a minute, Peter!" Steve calls back. He turns to Tony. "Come on."

Together, the two of them head into the kitchen, where they find Peter sitting at the table, his nose buried in a book. Steve goes over to the stove and starts to make their dinner, while Tony takes a seat beside his son.

The book Peter has in front of him is fucking huge, and Tony can't help but feel proud of how smart his eight-year-old is, because he doubts any other third graders would ever want to touch a book that large. But then again, Peter is the son of the genius Tony fucking Stark.

"What're you reading, Pete?" he asks.

"Harry Potter," he replies, a bit warily. "You…you're not angry with me, are you, Dad? 'Cause of what I asked you?"

Oh, great. This is exactly what Tony didn't want him to think.

"No," Tony says. "I'm not angry. Your question just caught me off guard."

"You told me Tony Stark never gets caught off guard," Peter says, smirking.

"Then this was the first time," he says smoothly.

"Sure it was, Dad."

Chuckling, Tony ruffles his hair. Steve comes over to the table, bringing over three plates full of spaghetti, and the three of them tuck in to their meal.

When dinner is finished, Steve is doing the dishes, Peter picks his book back up, and Tony is on his tablet, going over a new design for the Iron Man armor. Right now, he's actually relaxed, and silently wishes that maybe Peter will let the subject of the arc reactor drop for now.

"Dad?" Peter asks softly, looking up from his book. "Are you going to answer my question?"

Fuck.

Tony's mind immediately goes back to all the memories that he'd been trying to order to go the fuck away the entire afternoon. He'd finally managed it, and now he was back to square one. Gee, wasn't thisswell?

Was this his payback for being such an asshole for so many years? Because if it was, he realized the saying was true: karma was a bitch.

"Dad?"

"Peter, be patient," Steve says softly. "Some questions are harder to answer than others."

Tony groans internally. Shit, shit, shit! He knows Steve is trying to help, but he also knows that it'll probably lead to more questions. No, not probably, it will lead to more questions.

"But why is this a hard question to answer?" Peter asks.

"It's…complicated."

"What do you mean?"

"Um…" Steve shoots Tony an apologetic glance.

"It is complicated," Tony says quietly. "Complicated and not particularly happy."

"I sort of figured," Peter says. "You looked all freaked out when I asked."

So after asking a question that brings up horrible memories, and observing that it made Tony sort of kind of totally freak out, Peter wanted to go ahead and keep asking questions. Yeah, that made sense.

"Tony!" Steve scolds, cuffing him on the head.

Oh, shit. He'd said that out loud, hadn't he?

And the World's Biggest Douchebag Award goes to Anthony Edward Stark.

Tony puts his head in his hands and groans. Today just kept getting better and better.

"Look, Pete," he sighs when he picks his head back up, "I know you're curious, but this isn't something I like to talk about."

"No, I never would've guessed," Peter mutters sarcastically.

"Hey!" Tony says sternly. "Would you like me to answer your questions? Because I can very easily not do that."

"Yes," Peter says quickly, blushing.

"Then behave yourself."

He nods.

"This," Tony begins, pointing at the reactor in his chest, "is called an arc reactor."

"Wait, isn't that what powers the Iron Man suit?"

Tony nods. "Before I was Iron Man, I was the CEO of Stark Industries, but it was a lot different. I made nuclear weapons."

"Nuclear weapons? Like missiles and bombs? Dad…those things kill people! Aren't you a… um…what's it called? A phil-something. Not Coulson."

"A philanthropist," Steve supplies, laughing.

"Yeah, that's it! A philanthropist."

"I wasn't really one back then," Tony says. "I wasn't exactly the way I am now. I…I was selfish. Really selfish. I didn't care that I was making things that could potentially kill people. All I cared about was that I was getting paid a ton of money.

"I had to go to Afghanistan to give the people there a demonstration of what was called a Jericho missile. While I got ambushed by terrorists, a missile went off and I got pretty banged up. When I woke up from being unconscious, I was in a cave, and I freaked out when I looked down and a car battery had been attached to my chest by this guy named Yinsen."

"A car battery?"

"Yes, a car battery. When the missile went off, a bunch of shrapnel went everywhere, including into my chest. But Yinsen didn't want to hurt me, and he was very smart. He knew that a car battery had an electromagnet in it, and that would keep the shrapnel that he couldn't remove away from my heart.

"Later, the leader of the terrorist group offered to let me go free if I built him a Jericho missile. I knew he was lying. I agreed to do it, but Yinsen and I spent our time making an arc reactor. Well, that, and the first Iron Man suit. We knew that was our only way out.

"We removed the car battery from my chest and replaced it with the arc reactor. It worked a lot better than the car battery did. Over time, I improved it, and used it to power the Iron Man suit."

"So it powers the suit and keeps the shrap-stuff from going into your heart?"

"Basically."

"But…can't anybody remove it?"

"No," Tony says softly. "It's too far in for me to do anything about it, but as long as I've got the reactor, I'll be fine."

"What if something happens to the reactor?" Peter says, fear evident in his voice. "You…you'll die, won't you?"

Tony's heart melts. Because that expression on Peter's face, that fucking kills him. He looks terrified, and that's why Tony didn't want to tell him any of this. The poor kid looks like he needs a hug, so Tony pulls him into his arms.

"Pete, look at me," he commands gently. "Yes, the reactor is what keeps me alive. But I know exactly how it works, how to fix it, and how to make another one if I needed to. Everything's fine, kiddo. I'm not going to die anytime soon. Please don't worry about it, okay?"

"Okay," Peter whispers. "I'm sorry that happened to you, Dad."

"Don't be sorry," Tony says. "It may still freak me out, and I may not like to talk about it, but I can't change the fact that it happened. Besides, if it hadn't happened, I would probably still be a selfish bastard. There would be no Iron Man, and then I wouldn't have become an Avenger. And I wouldn't have met Pops, which means that we would never have gotten married, and we wouldn't have you. So I think things kind of worked out."

"Ew," Peter grimaces. "When did you get all sappy?"

"It's not sappy when it's true, kid," Tony chuckles.

"No, it's still sappy."

"Regardless of how sappy it is, you should be getting to bed," Steve interjects, smiling.

Sighing, Peter slides off of Tony's lap and starts walking toward his room. He stops in the doorway and turns.

"Dad? Pops?" he asks.

"Yes?" Tony and Steve reply.

"I love you guys."