Jean Grey does die in some story arcs of the comic books. However, comic book universes are complex, and her fate can change depending on the writer and the specific storyline.
One way is to look for fanfiction communities that have strict rules against adult or inappropriate content. Reddit has some great sub -reddits dedicated to Marvel fanfiction where users often recommend clean and interesting stories about Jean Grey. You can also ask for recommendations in these communities.
Yes, there are many. For example, some fanfictions explore her relationship with the X - Men in a platonic and growth - oriented way. They might focus on how she learns to control her powers, her leadership within the team, and her friendships.
The number of Marvel comic heroes is constantly changing and growing. As of now, there are well over 8000 characters, but new ones are always being introduced.
One possible fanfic could be about an original character who has a special connection with Jean Grey as Marvel Girl. Maybe the OC is a new mutant at the X - Men school and Marvel Boy, who is also there, starts to notice how the OC and Jean interact. The story could revolve around a mission where Jean's powers as Marvel Girl are crucial, and the OC and Marvel Boy have to learn to work with her.
It's a bit complicated. Jean Grey's fate varies depending on the comic storyline and continuity. Sometimes she's dead, but often there are plot devices that bring her back.