A common theme is the exploration of the unknown. Since Mephisto is often associated with mystery, fan fictions usually involve the reader character delving into Mephisto's dark and magical world.
Well, it depends on the writers' imagination and the direction of the story. Sometimes characters take unexpected paths, so Loki ending up there isn't out of the question.
One great piece of mephisto x reader fan fiction is 'Mephisto's Encounter' which has an interesting plot where the reader character gets involved in Mephisto's mysterious world. It's full of vivid descriptions and engaging dialogues.
The Avengers originated in Marvel Comics. Marvel has developed a vast universe of characters and storylines, and the Avengers are a key part of it. Their adventures have been adapted into various forms of media, including movies and TV shows.
Captain Marvel is Carol Danvers. She gained her powers through an interaction with alien technology and has become a powerful hero in the Marvel universe.
Marvel justifies Marvel Comics 1000 by presenting it as a celebration of their rich history and a platform to introduce fresh and exciting story arcs. It could also be a strategic move to attract new readers and reignite the passion of long-time fans.