Get in the car, kids. It's a massive a review.
I think you did a brilliant job writing Squall. This is exactly how I imagine him (and Rinoa, as well). He doesn't come across as cold and uncaring, but the reader gets the hint that while he has a rich and intelligent inner world, there's a definite block between his thoughts and what comes out of his mouth. His thoughts and actions relate, but something gets lost in translation.
Because of that, it's easy for the reader to like Rinoa. Despite Squall's inability to express himself, Rinoa is able to pick up that she's not getting the whole picture. She also comes across as being very sensitive to what she doesn't know while trying to work with the information Squall does give her. And she has her own walls, too. Their interaction with each other is interesting and believable - they're both trying to figure the other out, and they both come to some recognitions of their own. I guess what I'm trying to say is that you've written something very genuine between the two characters.
Other parts I liked: How you nailed the reluctant-leader part of Squall's personality. Even when he's entirely annoyed with everyone (ha ha, poor Squall), he's still thinking about what needs to be done to hold them together. Also: How you've written what he's thinking. It's not enough for him to think "this is how it is" or "this is how it isn't", but he also wonders "why is it like this?", "what do I think about it?" and/or "what do I do about it?"
In short: wonderfully written. Definitely a favorite.