No, Captain Marvel isn't typically considered the leader of the Avengers in comics. The leadership role often changes among various characters depending on the storylines and events.
Another fanfiction idea could be a prequel to her role in Avengers: Endgame. It could show what she was doing in the cosmos just before she received the call to return to Earth. Maybe she was facing a different threat that was related to Thanos in some way, and this backstory could add more depth to her character in the movie.
In recent comic arcs, Captain Marvel has emerged as a potential new leader of the Avengers. Her strength, strategic thinking, and determination have made her a prime candidate for the position.
Well, in a lot of 'Avengers Captain Marvel fanfiction', Loki can be a very interesting character. His mischievous nature can lead to all sorts of plot twists when interacting with Captain Marvel. Scarlet Witch is also popular, as her powers and Captain Marvel's can have some really cool and unexpected interactions, whether they are on the same side or opposing each other.
Captain Marvel and Thor make an interesting pairing. Their powers are both related to cosmic elements, with Captain Marvel having her energy - based abilities and Thor his godly powers. In a fanfiction, they could team up to battle some inter - galactic villains and their combined strength would be quite a sight.
Captain Marvel saves the Avengers by being a powerful force on the battlefield. Her energy manipulation skills allow her to create powerful barriers to protect the team or launch devastating attacks on their enemies. Moreover, her quick thinking helps them come up with effective plans to overcome difficult odds.