I have been writing fiction for over 20 years, and can still write unreadable fiction quite easily.
For those starting out in fan fiction, here are some articles that might help you out.
https://www.wikihow.com/Write-a-Fanfiction
https://hobbylark.com/writing/How-To-Write-A-Good-Fanfic
https://tvtropes.org/pmwiki/pmwiki.php/SoYouWantTo/WriteAFanfic
Things to avoid
Info dumps
https://ellenbrockediting.com/2014/07/03/novel-boot-camp-lecture-3-how-to-avoid-info-dumping/
In early science fiction, there were tons of dialogue that began, “As you know, Jim…”
Wolverine and Rogue serve many purposes in the first X-Men film.
One purpose is that, since they know nothing of Xavier’s school, they can ask questions. Also Logan can interact with the adults. Rogue with the student
Show Don’t Tell
https://jerryjenkins.com/show-dont-tell/
Dialogue
https://jerryjenkins.com/how-to-write-dialogue/
https://www.freelancewriting.com/creative-writing/6-tips-for-writing-compelling-dialogue/