Tony Stark makes his way into his home in the middle of the night after dealing with his announcement that he was Iron Man that actually went better than he anticipated.

Pepper Potts is also gone for the night, meaning he'll be by himself for a while.

Tony enters his home, but notice the lights haven't been turned on automatically.

"JARVIS?" Tony calls out.

"Welcome home, Sir..." JARVIS answered distortedly, then drones out.

Tony then sees a figure standing by the window of his living room, behind a long couch, looking out into the ocean. Tony worries if Obadiah Stane survived and is back to finish him off.

"'I am Iron Man,'" a deep voice echoed through the room, quoting Tony from the press conference. Tony doesn't know who it is but it's definitely not Stane's voice. "As if cosmic rays, gamma accidents, radioactive bug bites and assorted mutants weren't enough, I have to deal with a spoiled brat who doesn't play well with others and wants to keep all his toys to himself. You think you're the only superhero in the world? Mr. Stark, you've become part of a bigger universe..."

The mysterious stranger then turns around and circles around the couch. "You just don't know it yet."

"Who the hell are you?" Tony asks.

The mystery man respond by revealing himself from the shadows. A tall African-American, possibly in his late-30's or early-40's, bald, dressed in all black leather and wears a matching leather eyepatch over his left eye, which covers a noticeable scar.

"Nick Fury, director of S.H.I.E.L.D.." He introduces himself.

"Ah." Tony respond nonchalantly, remembering Phil Coulson is part of his organization.

"I'm here to talk to you about the Avenger Initiative." Nick explains why he's here.

"Well, what are we avenging?" Tony asked, confused to what the Avenger Initiative is.

"Whatever the hell we want." Fury said with a smile.

Author's notes:

Based on an earlier take on the Iron Man post-credit scene, which Kevin Feige apparently wanted to feature Spider-Man and the X-Men in the MCU as early as Iron Man.

Even with the post-credit we got in the movie, I always assumed all the pre-MCU movies take place in the same universe, with Fury saying he's not the only superhero confirming that. As well as the early script of Iron Man revealing that Tony created Doc Ock's tentacles and Tobey Maguire cameo in The Incredible Hulk.

I plan to write a series of MCU fanfics which includes the Blade Trilogy, Fox X-Men movies, Spider-Man Trilogy, Tim Story's Fantastic Four movies, Daredevil/Elektra, The Punisher (2004), and the Ghost Rider movies. Thus, "radioactive bug bites" specifically refers to the Tobey Maguire Spider-Man and "assorted mutants" specifically refers to Fox's X-Men. "Gamma accidents" specifically refers to the events of Hulk (2003), which The Incredible Hulk is a sorta-sequel to. Hence "Bigger Universe".

I added "cosmic rays" in Nick Fury's dialogue, which refers to the Fantastic Four.

Which means these versions of the characters will replace their MCU counterparts, but will also have some of their backstory. There would also be characters and elements from Punisher: War Zone, The Amazing Spider-Man film series, and even Fant4stic mixed into it.

It's also why even though this happens in Iron Man, I placed the story in the Avengers (Movie)/Movie X-overs category.