World War 2 Era
~Super Soldier Serum developed by Dr. Abraham Erskine in Germany at the start of World War 2. Johann Schmidt takes the formula, becoming the Red Skull. Erskine escapes to America, being involved in the Strategic Scientific Reserve, and then Operation Rebirth.
~Schmidt becomes lead of Hydra, finds the Tesseract. Starts to create weapons with Arnim Zola. The Super Soldier Serum is administered to Steve Rogers, who then becomes Captain America.
~Defenders aid the Allies.
~The events of Captain America: The First Avenger, essentially. With one difference, the Tesseract is never recovered by Howard Stark. Bucky is taken by Hydra and made into the Winter Soldier.
~Logan participates in World War 2. Meets Captain America as his squad and the Howling Commandos liberate a Nazi internment camp of Jewish citizens.
~Erik Lensherr and his family are put into a Nazi internment camp, his family killed before the cap he was in was liberated.
~21 years ago, the first publicized major mutant 'incident' is reported. A single man disables a Russian submarine, all hands lost. Mutants, almost immediately, are seen as a force of destruction to the world as a whole. Up to this point, mutants were more urban legends. The ones that are 'discovered' are treated with prejudice, sometimes to the extreme. But it is never reported.
~10 years ago, Charles Xavier begins work on a school in upstate New York with the intention of someday having it act as a safe haven and learning center for mutants. It has yet to be opened to the public. He has taken in a small handful of mutants, helping them to gain control over their abilities.
~8 years ago Tony Stark premieres as Iron Man. He is approached by Nick Fury to aid in the Avengers Initiative. Thor arrives on Earth, his battle with the Destroyer leveling a small town. Captain America is found in the ice and revived by SHIELD. He begins assimilation into this new world. He has yet to be revealed to the public.
~2 years ago Reed Richards heads a research team to launch an experimental spacecraft for stellar study. After exposure to a stellar storm, it crashes back to Earth. The team of 4 gains new abilities, but have yet to be revealed publicly.
What else? I'd like everyone's input on this. And the updated roster..
X-23 - Camleen/Ashley/ME!
Wolverine - Dipper
Deadpool - Dunruffle
Noir Spiderman, Penance - The Wanderer
Average Joe' utility guy! - Furasian
Steve Rogers - MST3K 4ever