For me, what sets this apart from other angst pieces is the nakedness of the fisherman's final line - not harsh, but brutal. There are other unique aspects - the haircut, "nineteen showers and a week later", the details about Cid and Squall - also the focus on her new cadets - but that line delivers the punch to the stomach.

As far as critting this goes, everything here is done quite well, so I have to focus on details, individual words, etc. I hope you don't mind, I think this is the only way I can usefully critique you.

Crits:

Instructor doesn't need to be capitalized.

"eviscerated intestines" - I'm not sure, but seeing as intestines are already viscera, I don't think they themselves can be eviscerated. Maybe "exposed intestines"?

I'm divided over whether the bit with the sharks is necessary - it sets a mood, but so does the rest of the scene.

"She is indifferent either way" - "either way" could be removed

Personal taste, but I don't think you need the italicized words. Your prose is strong enough that the words carry enough impact without it.

"gravity got turned around backwards" - could remove "backwards"

"reinstated on dedication" - maybe "reinstated for dedication"?

"rejected the offer down" - "down" is unnecessary

"and[,] occasionally, Seifer Almasy"

"even though Squall had taken great pains..." I think I see what you're getting at, and it's a good detail, but it's a bit like a non sequitur phrased that way.

"the grimy tug of nonspace...while tugging a brush" - awkward repetition; "strands that[,] frankly, weren't worth"; Also, the sentence is long and could be broken into two.

"and nor would it be the last" - "and" is unnecessary

A pound of hair? That's a lot of hair. If you're being hyperbolic, I'm not sure the fic calls for that.

"anything reasonably leveled" - Would they refer to the enemies as having levels?

"There was a funeral with...caskets and "; "sound instructor and" - no commas needed

Another preference thing, but I think you could have ended the story more subtly on "next week's lessons". It implies everything that the final two lines say outright. If you keep those lines, I don't think the italics are needed on the "can't" - it feels like you're browbeating there. The reader can sense her guilt and determination already; we don't need a visual cue.

End crit:

My crits are mainly nitpicks, which is a sign I enjoyed this a lot. It's strong writing, particularly towards the end - the dry recounting of the massacre, and the way Quistis' thoughts from the present ("It is the only thought that she can remember having, and it haunts her") punctuate it very well. It's also a hard fic, towards the end, because it shows that not everything turns out perfectly, even after a happy ending.

Quistis has such a bad run as an instructor. Love your summary line.

Poor Quistis.