Peter Parker's cameo in Iron Man 2 has been one of the more persistent Marvel fan theories in recent years. Near the end of the 2010 flick, a young boy in an Iron Man mask at the Stark Expo (in Queens) defiantly stands up to Hammer drone, only to be saved by Tony Stark himself seconds later. "Nice work, kid," Iron Man says before flying off.
For years, fans speculated that the kid in question was actually little Peter Parker. As it turns out, they were right.
"I can confirm that as of today. I literally had a conversation with Kevin Feige only 20 minutes ago. Maybe I've just done a big, old spoiler, but it's out there now," he said. "It's cool. I like the idea that Peter Parker has been in the universe since the beginning."
OK, so there's a high possibility that Feige is just doing some serious retconning. After all, we never see the child's face, and at the time Iron Man 2 was in production, Sony hadn't even released The Amazing Spider-Man, starring Andrew Garfield as the titular webslinger. Sure, it's possible that Marvel had begun initial negotiations with Sony to let the popular comic book character enter the Marvel Cinematic Universe as soon as 2010, but it was by no means a done deal. (Negotiations didn't even begin to get serious until after The Amazing Spider-Man 2 disappointed at the box office.)
Although, given the fact that the Stark Expo did take place in Queens roughly seven years ago, it's perfectly plausible that an 8-year-old science geek like Peter would attend the tech conference. So it could have been a major Easter egg for savvy Marvel fans to figure out. Either way, we'll give Feige credit for wanting the kid to be Peter Parker.
Bringing Spidey into the MCU means that The Powers That Be have established a canon in which Peter Parker, now 15, was just a city kid when the battle of New York happened at the end of The Avengers. He's quite literally grown up with the Avengers in his backyard. They're his hometown heroes — and to think it all started seven years ago at the Stark Expo is pretty cool. With that context in mind, Peter's desire to become an Avenger in Homecoming makes total sense.
Not to mention, it foreshadows his father-son dynamic with Iron Man.