Hmm. Near as I can tell this hasn't been mentioned previously. Possibly because it's original serial webfic rather than fanfic (is there a hard fanfic only rule for the thread?) but I have to recommend Spots the Space Marine which is an ongoing serial by M.C.A. Hogarth (aka Haikujaguar on LJ). Set on an outpost during a war between Humans and an alien ally against alien bugs that want to devour everyone else.
Yeah, old SF plot, but the characters and the writing make it work. The writing is a touch sparse, somewhere between prose and a script, but works well at pushing the story forward. The first few chapters are a little rough, as interestingly enough this didn't start with the intention of telling a story but as the authors way of tracking her workouts. Only once she created one character she created another, and next thing she knew there was a plot and story reaching out saying, "Excuse us, but we don't feel like being held hostage to your time spent on an elliptical trainer."
-----
Will the transhumanist future have catgirls? Does Japan still exist? Well, there is your answer.
Yeah, old SF plot, but the characters and the writing make it work. The writing is a touch sparse, somewhere between prose and a script, but works well at pushing the story forward. The first few chapters are a little rough, as interestingly enough this didn't start with the intention of telling a story but as the authors way of tracking her workouts. Only once she created one character she created another, and next thing she knew there was a plot and story reaching out saying, "Excuse us, but we don't feel like being held hostage to your time spent on an elliptical trainer."
-----
Will the transhumanist future have catgirls? Does Japan still exist? Well, there is your answer.