Do Steve and Bucky learn that Peter talked to Sarah? And do they talk to him too?
Sarah does eventually tell them because she loves Peter but she also wants to protect Tony. She knows that Peter would still love his mother regardless of what, exactly, happened to him, but she also knows that Tony kept it from his children for a reason. Peter will look at Tony differently–perhaps not with pity, but with something, and it’ll make Tony feel awful. And to be honest, Peter doesn’t need to know anything. It’s in the past and it’s none of his business. She put it in context for him (it’s nice you have parents right??? because Tony didn’t for most of his formative years) but that’s all the information she was ever going to give her grandchildren.
Steve and Bucky are… not pleased, but also not surprised. They were kind of just waiting for it to happen. Their children were curious to a fault so they’d have asked at some point. They just don’t like the way Peter went about it, going to ask Jarvis first. Jarvis is even tighter-lipped about what happened in the Stark castle than Tony; he’s ashamed that he couldn’t do more to protect his friend’s son. Ana has quietly admitted that she’s pretty sure Obadiah tortured Jarvis, psychologically if not physically, by threatening Tony. Jarvis won’t tell her, of course, but she’s almost certain that Jarvis would have attempted to be more hostile if not for his concern for Tony. He’d once called Howard his best friend and then backpedaled and added “as much as a king could be a friend with his servant.”
(Duchess Margaret had told her that Howard adored Jarvis. She’d visited Howard a few times before he died, and Jarvis had always been by his side. When Howard had come to visit her once (she needed help getting her people set up with the irrigation system Howard had designed) without Jarvis, he had said, “Maria’s pregnant, Peggy. If there’s anyone I trust my wife with, it’s Jarvis.” Duchess Margaret had laughed, because Howard probably had someone more than a beta protecting his wife. Except he hadn’t. Jarvis waited on Maria hand and foot and when she tried to protest Jarvis was earnest about how much he wanted to help her, and how he hoped she would allow him to watch the baby someday. Maria couldn’t imagine anyone better suited than someone that already loved her unborn child simply because it belonged to her and Howard to take care of him.)
They talk to Peter, tell him that he is under no circumstances allowed to ask Jarvis about what happened in Stark castle. Tony would never forgive him. He is also under no circumstances allowed to ask his mother what happened in Stark castle. Tony still bears the scars, both physical and psychological, of what happened to him growing up. Peter nods meekly. He hadn’t planned on asking his mother anything after thinking how awful it must have been growing up without parents. The grave way his fathers are speaking to him makes him realize he’d really stuck his nose where it didn’t belong.
(Peter sneaks into his parents’ room and carefully crawls over his dad’s body like he had when he was a child to flop on top of his mother. Tony grunts. “Oof, Peter, you’re too big for this.” “Mama,” Peter asks softly, and ignores the way his fathers stiffen on either side of him. “Do you really hope I’m happy with Matt?” Tony blinks at him blearily. “What? Of course. Why is that even a question. All I’ve ever wanted is for my babies to be happy.” Peter thinks about it a while before asking, “Can I name one of my kids after you?” Tony snorts. “You can name your kids whatever you want. I will give them pet names if I don’t like them.” “Mama!” Peter gasps, offended, and Tony snorts so hard he knocks his head against Bucky’s. “Owwhatthefuck,” Bucky moans, clutching his head, then turns so he’s facing away. “Go to sleep, you hellions.”)
((“How in the hell,” Steve grunts when he realizes that he doesn’t have his arm around Tony, but Peter. Bucky sits up groggily. “…Harley, when did you get here?” “Shh,” Harley whispers. “They’re sleeping.” “It figures that you would be the problem baby but the angelic teenager,” Steve grumbles.))