Oneshot, edging into darkfic. Requires reading into and hopefully won't be eaten by the site again.
At first, he almost panics.
Gaara knows that Sakura only treats him with the familiarity he's become accustomed to because of her teammate. So the friendly gestures, the near-affectionate tone she uses when addressing him, the almost-believable flirtation, the trust she shows by letting him into her home – they don't matter. And they don't have to. What matters is Naruto's happiness.
So he tries to explain it to her – at first quietly, trying to sound rational, then a little more loudly when she starts to argue with him. Then their voices are raising in tandem, the neighbor is pounding on the wall to make them shut up, and he just can't understand why she's disagreeing, why she's saying that she isn't sure she could just give the blond a chance, why she thinks that she needs time to come to any sort of decision when he knows as well as she does that she's just stalling, that she doesn't have a real answer. He tries to explain that he knows she'd be able to look past the Kyuubi to accept Naruto for whatever he could be, she'd be able to do anything because she's got the heart and soul of a medic and he's certain she'd give up everything in order to stop a person from being in pain... But by that point the words aren't making any sense and she's trying to herd him out of her door.
He's not sure what he intends when he grabs her – maybe to stop her from reaching the doorknob, maybe to force her to just listen for once – but she doesn't resist him, and he figures things out quickly enough from there.
ooo
Afterwards, she almost panics.
When Gaara rolls off of her to stare, panting, at the ceiling, she doesn't know what to think. Her lips are swollen and sore, the bruises his grip has left on her arms and body are starting to ache, and there's a raw, deep pain encompassing almost her entire pelvis – but she can't pay attention to that, because he's touching his own face, he's shaking more than she is, and if she doesn't move fast then all hell could break loose from right beside her. So she gathers the remains of her clothing around herself like the shreds of her innocence and tries to offer him what reassurance she can.
Sakura understands she's encouraging him to reach for her again at some point when she tells him everything's all right. By the time that happens, though, she's almost convinced herself she has nothing to lose by letting him. The first time might have been quick and hard and ugly, as the two of them tore at each other's clothes on her floor, clashing with equal parts anger and lust and fear – but the next time they make an effort to undress each other, his kisses and hands are gentler, and the sounds she makes as he pushes into her are of pleasure.
In time she understands that it's not about sex, it's about intimacy, in the same way she understands her incapability of having a physical relationship without becoming deeply emotionally attached as well. But if, after every time, Gaara holds on to her for a little longer; if it becomes a little harder for her to let go, to pretend she doesn't crave his skin, his strength; if his demeanor becomes a little more desperate; if their casual interaction becomes stilted and forced to the point that Naruto starts giving them curious glances... then she has to recognize things can't continue like they are.
"It shouldn't have been like this," Gaara tells her. She inwardly cringes at the shame in his voice and presses his head to her shoulder, because she's finally realized what he was trying to tell her before, what he was trying to accomplish: attempting to push one of the people he wanted at the other, only to find she wanted him more. "This..." His fingers move against her arms in a way she knows indicates their closeness rather than how he's still in her. "It's something he deserves."
"But what do you deserve?" she asks.
He doesn't answer. And she knows what she can do.
It's not as hard a decision as she'd thought it would be.
ooo
Until he understands, he almost panics.
The two had gotten weird, yeah – but that isn't a big deal. What matters is that Naruto's sure they're not getting along, that Sakura's forcing herself to be polite or that Gaara's getting pissed off and could snap at any given moment. He wants more than anything for his important people to be friends with each other as well; so he invites them over, then makes them sit down while he paces and tries to figure out what to say.
"Are you sure?" he hears Gaara ask, and spins on his heel to find out what's wrong, because that couldn't possibly be Gaara's voice – Gaara doesn't sound unsure, ever, that's just not how the guy works – but freezes when he sees them. Sakura's practically in Gaara's lap, an arm draped around the redhead's shoulders in a way that speaks of long familiarity, nodding in response to his question. Then, to make everything that much worse, she leans in and kisses him.
Watching them, Naruto feels his heart sink to somewhere in the pit of his stomach as his throat clenches so tight he can barely draw breath. And he almost panics. Almost.
But then they both turn to look at him, faces free of guile, or challenge, or anything he could possibly take offense to. He calms down, forces himself to swallow past the lump in his throat because he understands what they've worked out, what they're saying: That no matter what was going on between them, neither would intentionally try to exclude him.
And it's their agreement, the utter sense of belonging which stems from this realization that leads him to accept. Naruto takes Sakura's shyly proffered hand and sinks into the space that Gaara makes for him on the couch, having resigned himself to figuring out exactly what he's supposed to do with this sudden, welcome complication to his life. The two with him, he finds out, are happy to help.