One of my favorite fanfic authors who does not post on Trek BBS (as far as I am aware) is Selena
. I haven't read all of her stories related to various fandoms yet, but here are two DS9 fanfics I really enjoyed. Both are based on the same concept of "five things that never happened", 5 AU stories that take the events of certain episodes of DS9 into a different direction from what actually happened on the show and explore how things might have turned out. The first one out of these explores the Kira/Dukat dynamic, and the second one the Bashir/Garak dynamic. They're pretty dark, have really good characterizations... and amazingly, neither is porn
Five Things Which Never Happened
Five roads not taken between Kira and Dukat. Exploration of a relationship. NOT a romance.
Paths Not Taken
Five things which never happened between Garak and Bashir.