Harry Potter and the Methods of Rationality: Eliezer Yudkowsky's fanfiction is exceptionally good. If you're a reader of LessWrong at all, you'll love it. If not, you still might like it. He wrote it in "serialized" format where each chapter is a mostly self-contained adventure with plot arc, and then a cohesive whole. It works well, reads well, lots of good insights. He didn't really hit his stride and tone until chapter 15 to 20... if you like Yudkowsky's normal writing, give it until chapter 20. Trust me on this - Eliezer sets up a lot of backstory and forces some humor in the early chapters, and the tone isn't quite smooth... still good, but then wow, it kicks into overdrive around chapter 20 and it's just a page-turning must-read. It's free online at and you can also find pdf compilations with some googling.