I Found
Most fanfiction would not infringe on copyright because it alters the text/original property in a “meaningful” way. Just like the argument against obscenity laws, it is difficult to argue what is artistic commentary, and what is copying. The example I could think of violating copyright infringement is a songfic that contains the entirety of the original lyrics. But even then one could argue they are modifying the lyrics enough with the additional text?