There's a fanfic called 'X - Avenger Team - Up'. It's a shorter but very engaging read. It focuses on a specific mission where a small group of X - Men and Avengers have to work together. The dialogue in it is really well - written, making the characters feel very true to their original versions. It shows how their different personalities can either clash or complement each other during the mission.
Some xmen fanfic stories center around alternate universes. In one such fanfic, the X - Men could be in a world where mutants are the dominant species and humans are the ones being persecuted. This would completely reverse the normal dynamic and force the X - Men to make different choices and face new moral dilemmas.
In certain comic arcs, Pietro's fate is that of death. However, comic universes are complex and his status can vary depending on the specific storyline and alternate realities.
I'm not sure who the absolute best is, but there are many talented writers in the fanfiction community. You can start by looking at popular fanfiction platforms and checking the reviews and ratings of Peter Maximoff - related stories. Writers who have a deep understanding of his character, like his quick - witted nature and his love for speed, tend to write great fanfiction about him.
Wanda and Pietro did not date in the comics. Their connection is that of brother and sister, and the storyline doesn't depict them in a romantic relationship.