I liked Lelani--she's an interesting commandant, and a good repeat OC to use for future works, I think. I also liked your take on Cid and Rosch as an excitable and pompous youth. They felt right to me, and I'd like to see what you do with them and their developing relationship. The idea of them knowing each other would be fascinating, given their individual storylines and ultimate fates. Connecting this up to the game's plot, would also be a fun alternate POV of events. Seeing Jihl again would be fun, too--she's interesting to me.

Things I could think of, very minor issues, are the world-building. Most of the doors we saw do the sci fi sliding open, and the environment seems controlled so few people ever finds things too much of one temperature. And since they have fal'Cie to control everything, even doors, I wonder about the AC breaking down--what happened to the fal'Cie who controls that? A few little details from Cocoon's unique, hyper-controlled environment could really liven up a piece and set the tone.

Overall, a nice excursion and good jumping place for future works. Your prose is clean and readable, so that is also refreshing!