Star Trek this time.
Here's my take on fanfiction:
While technically illegal, a bunch of 14 year olds writing about the characters they've fallen in love with (often porn*), and stretching their literary muscles (mostly with cringe inducing results), is mostly harmless.
Provided they do it on a fan fic site to share their little fantasies with other rabid fans, and bask in the glow of a similar interest.
Once said fan writer decided (usually erroneously) that they should be paid for this effort, and offer a highly illegal copy of someone else's intellectual property for financial gain, they should be gutted with a spork.
*there may be nothing on Earth unintentionally funnier than a sheltered tween's idea of how sex works.