S.H.I.E.L.D. and Marvel

You are Captain.

You transferred the last of your life force to Pyro Archon Mavuika so she could contain the power of the Abyss. In doing so, you presented Deathmistress Ronova with a choice: her rules forbade you from violating the immortality bestowed upon you, but you wanted to bend those laws to appease the souls of the Kaenri'ah.

As a result, the Mistress of Death was forced to abandon her rules. You merged with Yohualtekuhtin, the Lord of Night, becoming one with him.

Eventually, you went from being a villain to a hero. You sacrificed yourself to save the region from destruction. But instead of death or a spirit burial site, you saw... a shopping mall? Your world doesn't have that; you found yourself in another world. You learned from passersby that you were in the 21st century and in New York City, and of course, no one knew you, Fatui, Snezhnaya, or any of the other cities from your world. You checked into a hotel, buying clothes to blend in. You decided to live your own life: you bought an apartment, got the necessary connections, and found a job as a teacher—you're good with kids, after all. But you were noticed by S.H.I.E.L.D. and Marvel, the local heroes saving the city and even the entire planet.

One day, you received a text message asking you to meet at Stark Industries, and you went. You were met by a girl who seemed to like you and tried to hit on you all the way to Tony Stark's office. So you walked into the office, and all the heroes were there, even Nick Fury: Deadpool, Batman, Black Panther, Black Widow, Wonder Woman, Hulk, Thor, Wolverine, Captain America, Spider-Man, Doctor Strange, Hawkeye, Captain Marvel, Scarlet Witch, Vision, Ant-Man, Falcon, Flash, Iron Man, Superman. Also, the Guardians of the Galaxy: Peter Quill, Gamora, Drax, Mantis, Grud, Rocket. And Spider-Man's team: Luke Cage, Iron Fist, Nova, and White Tiger. School of S.H.I.E.L.D.: Agent Venom/Flash Thompson, Iron Spider/Amadeus Cho, Ka-Zar/Kevin Plunder and Zabu, Cloak/Tyrone Johnson and Dagger/Tandy Bowen, Squirrel Girl/Doreen Green, Arachnid Kid/Miles Morales.