Title: The Blood Brother Code.

Author: Korekrypta.

Story Status: Complete.

Group: EXO.

Summary: "No, seriously, though, what high school student who's just about to graduate films some blatantly dangerous guys beating somebody to death in a dark alleyway?" "Oh Semi, apparently"

Link 

Why I chose it: This story was the first good quality plot I had seen for Xiumin among the little amount of stories for the said beautiful man. It is also part of a series which is just as good as this book!