Earth-91999 is a world in the multiverse that is different compared to its main counterpart, Earth-7728
Here in this world, the Avengers aren't a thing until 2014. They came together after Hydra's successful infiltration and control over S.H.I.E.L.D
After WW2, Steve Rogers managed to stop Red Skull before taking off in his jet. He lived a happy life with Peggy Carter and both had a daughter named Sharon Rogers who takes up the Captain America role in modern day
Gwen Stacy is bitten by the radioactive spider instead of Peter Parker, and she becomes Ghost-Spider
Charles Xavier was assassinated before the X-Men were assembled. With his death, the X-Men never came to be
many groups of heroes exist to defend earth and protect the innocents. This world has a few heroes, nothing too crazy and eventful is happening every day
The Avengers are the most known heroes that were formed in 2014 when Hydra was taking over S.H.I.E.L.D. Using S.H.I.E.L.D’s weapons against the citizens of the United States, many were killed. Both human and mutant alike. Wanting, to avenge those killed; Sharon Rogers, Jean Grey, Bruce Banner, Natasha Stark, James Rhodes, Natasha Romanoff and Clint barton rose up to fight against Hydra. Thor eventually joined the battle when he learns that Jane Foster is among the killed. After defeating Hydra and hunting down the remaining bases around the world, putting their terroristic attacks at an end for good, the team formed the Avengers and protect the people and defend the earth. Their base is at Avengers Compound which is in upstate New York
Gwen Stacy became the vigilante known as Ghost-Spider when she got bit by the radioactive spider at Oscorp during a field trip. She was reckless and naive but it all changed when her best friend, Peter Parker turned into a Lizard to be like her and help people. the lizard serum mutated him and during a fight with Ghost-Spider, she accidentally killed him. Gwen became depressed for a while and gave up the role for a while until she managed to get out of that dark place. When she became Ghost-Spider again, she is more careful and uses her powers responsibly
The assassination of Charles Xavier is a mystery. Xavier was a good man to both humans and mutants, his death is mourn by both sides. Some mutants are angry and believe that a human killed him. Jean Grey was taught by Charles on how to use her powers, she owes him a debt and tries to find his killer ever since she joined S.H.I.E.L.D and when the Institute closed forever.