This is a good point. While fan fiction authors generally don't have a legal right to make derivative works, the copyright owner isn't obligated to sue them, ei

This is a good point. While fan fiction authors generally don't have a legal right to make derivative works, the copyright owner isn't obligated to sue them, either. This article is a good overview of the copyright issues around fan fiction: https://blog.jipel.law.nyu.edu/2021/04/is-fanfiction-legal/ https://blog.jipel.law.nyu.edu/2021/04/is-fanfiction-legal/. It notes "While on their face, these fanfiction communities may seem like harmless outlets for fans, existing copyright doctrine actually renders much of these works as infringements of copyright. The problem is that most fanfiction could be characterized as derivative works of other already existing original works, as defined in 17 U.S.C. § 101." Marvel clearly tolerates online fan fiction to an extent, but I imagine if someone tried to publish an illustrated anthology of Marvel fan fiction and sell it on Amazon, or make and release a film based on it, they would probably find the limit of that tolerance.