Weave, weave the sunlight in your hair.
The title is taken from the 31 Days theme for March 18, 2009.
It takes Roy Mustang a few years to realize that Riza Hawkeye is growing her hair out. He's not supposed to miss those kinds of details, mind you, and he's a little ashamed over the fact that he missed such a thing when it was happening right next to him/right behind his left shoulder, but maybe he shouldn't be surprised. If he's not tired he's busy and if he's not busy he's tired and she's just always within his peripheral vision either way, alternating between quietly working and quietly telling him to get back to work, sir.
So either way, it takes him a few years, and it would have taken him longer if she hadn't decided, one particularly cold day, to remove her clip to keep the draft off her neck and Roy looks up from twirling his pen and a boring report in time to see her shaking it out.
To Roy's credit, the pen does not drop; it skips over two knuckles instead of one.
A moment later, though, he's forced to stop admiring the way Riza looks with her hair down because the sunlight's at that right angle where it's harsh on any woman who's been through too much and Riza certainly fits the bill. He sees it: the slightest crinkle about her eyes, betraying a not-so-slight lack of sleep, and there's this particular way that she brushes a strand away from his ear that makes him think that really: maybe it's best if she stopped following him around. He can find another person to keep her crosshairs on his back. Someone more expendable. Someone who could come to matter just a little bit less in the future.
Roy tries to bring this up, in a roundabout way, when they're alone in the office eating lunch and drinking coffee. Riza stares at him for five full seconds before informing him, matter-of-factly, that he is making no sense and with all due respect, hurry up with your meal, sir, because there's a stack of papers gathering dust in the archive and she wants each one of them signed by the end of the day.
Later, Riza goes home to her apartment, feeds Black Hayate, sinks into the hot water of her tub and wonders if it was just her imagination, or if her colonel's eyes really did look that sad.