FicWad

I enjoyed this story, and rather like the concept of "counterbalance" that you created between day/night, Riza/Havoc, coolness/closeness, and so on. I'm not entirely sure that the Mustang we know would let both of these people in, let alone one of them, but it's fascinating to speculate. One tiny little thing leaped out at me in the first paragraph that you might consider, to smooth out your style a bit: you used the words "day" or "days" five times in that one paragraph alone. It's usually better not to let that sort of repetition creep in, unless it's to create a deliberate, specific effect. So you might consider some synonyms, or a slight rephrasing, to avoid that repetition, because it does make the eye catch and keep it from reading smoothly.