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i.
The first time happens; Mitsuki swears it is a mistake.
Hiroomi is sitting on the edge of the bathtub, wincing and pale and bleeding all over the pristine white floors, and Mitsuki feels her heart stutter to a stop, her throat closes and her eyes water. She’s unused to seeing her brother like this. In her dreams, Hiroomi and Izumi are fearless and indestructible, they are gods.
She is on her knees in front of him before she even knows what’s happened. His brows furrow when he notices her there—and he must truly be injured, because he always notices her. “Mitsuki, no, I can handle this—“ he stops with a groan, hand pressing harder into his side.
“Stop,” she commands, grabbing his chin. “I can help you. Let me help,” Mitsuki adds, softer. She gives him her best smile and leans back, reaching into the cabinet for the first aid kit Izumi keeps under there. “What happened?”
“Apparently,” Hiroomi begins heavily, determined not to look at her as she gets to work cleaning out the scratches across his ribs, “Tree youmu are much fiercer than one might think.”
Moron, Mitsuki thinks fondly, letting her finger trace along the edge of one slash. He stiffens under her touch. Raising her eyes to his face, she smiles softly. “I have to use peroxide. Squeeze my shoulder if it hurts too badly.”
“Alright,” Hiroomi nods, resting his hand on the curve between her neck and shoulder. His long fingers are warm with his blood, but she doesn’t mind; she needs to shower before bed anyway. The first touch of peroxide has him tensing up, squeezing her almost painfully, but in the next few minutes he relaxes, fingers sliding around to cup the back of her neck, thumb rubbing the sensitive skin behind her ear.
Mitsuki pretends her face isn’t on fire, though she’s sure she looks like a tomato.
Soon, he is taped and wrapped, only faint traces of red on his skin showing that there was any blood at all. “There,” she murmurs, shivering when his fingers sift through her hair, cup the back of her head. “All better.”
“Just what a big brother needs,” Hiroomi teases—or maybe he doesn’t, his voice is thick with something she pretends she doesn’t recognize—and she raises her gaze to meet his. “His little sister.”
“Don’t be a pervert,” the words are soft, barely there, and she doesn’t wince away when Hiroomi kisses her softly. In fact, she presses her mouth firmer against his, fingers shaking as they rise to grip his face. He gasps when she touches him, and Mitsuki takes the chance to deepen the kiss.
ii.
The second time…well, this time, Mitsuki does actually mean to.
They lie together in Hiroomi’s bed; hands clenched tightly, the same blonde haired boy on both their minds. It is on the tip of her tongue to mention that the next time he goes berserk, they’ll need to kill him, but Hiroomi has so many things on his mind that she refrains for now.
His thumb traces over her knuckles, squeezing every few minutes, as if to remind her that he’s there. But it’s not as if she can’t tell because she always can, especially when he’s this close. She’s hyper aware of how close he is, can feel it with every fibre of her being. It should make her sick, how much she feels for her brother but the nausea doesn’t rise in her throat like she thought it might, and her skin doesn’t crawl like she knows it should. If Izumi ever found out, if she even suspected something like this…Mitsuki couldn’t imagine what her sister would do. Kill them, maybe, which would be awful. Or separate them. That would be infinitely worse.
Mitsuki cannot lose Hiroomi.
She’s thinking about this as she drags his hand over to her, to the waistband of her tights. She releases his hand then, resting it on the bed between them. Hiroomi’s gaze is hot on the side of her face, his fingers long and teasing her skin. He asks, “Are you… Mitsuki?” And she nods, yes.
His hand slips beneath her waistband, torturously slow, and then he’s slipping his finger between her folds, toying with her clit. It feels different than when she touches herself. His fingers are rougher, longer. They slip into her with ease, first one, and then a second. He’s moving to lie over her when she bucks up, cries out. His mouth closes over hers, kissing words like, “quiet,” and “beautiful,” and “Mitsuki.”
She comes almost embarrassingly quickly, but he doesn’t seem to mind, if the lazy, happy smile he gives her is anything to go by.
“I love you,” he tells her, nuzzling behind her ear, and Mitsuki sighs, digs her fingers into his sides.
“I love you, too,” she breathes.
iii.
“You almost died,” Hiroomi presses heated, feverish kisses to her face, her neck. His lips ghost across her eyelids and cheeks, teeth bite her lip and then lick away the pain. “Gods, if you’d died I would—I would have—“
“Shh,” Mitsuki soothes, pressing her mouth to his. But Hiroomi is not in the mood for anything slow, and they are alone in the house, so he pushes her up against the wall, fitting himself easily between her legs. He’s already hard; pressing against her through his pants. Mitsuki bites her lip at the feeling of him, but he tugs her lip out from between her teeth, sucking it into his mouth.
“I’m right here,” she says between kisses, rubbing herself against him. His fingers are ripping her panties, her good panties, but Mitsuki can’t find it in her to care. She did almost die, that youmu had been choking her and she’d been so sure that she was a goner; that nobody would get there in time. The bruises are just now showing up on her neck, and Hiroomi presses soft, open mouthed kisses to them, whispering words of apology into her skin. “I’m not leaving.”
“Swear it,” he pulls away, holding her face between his palms, pushing her more firmly into the wall so he doesn’t drop her or have to relinquish his hold on her. “Swear to me that you will not leave.”
She knows that she can’t. Part of being a Spirit World Warrior is death—her parents knew that best, and look where they are now—but she also knows that Hiroomi will not take no for an answer, that he knows the true answer, so she feels that it’s alright to lie to him, perhaps just this once. “I swear to you, Hiroomi that I will not die.”
He crushes his lips to hers.
iv.
It is so wrong, this love she feels for her brother.
It’s sick and illegal and she knows but Hiroomi looks at her like she is the sun and he is the moon, and he would die for her. Die for her, and that isn’t something you find every day. Izumi says Spirit World Warriors are destined to die alone, destined to be alone and so this seems like an easy alternative.
She doesn’t know if any other boy would ever feel this way for her. She doesn’t know if she wants any other boy. Akihito had seemed like a good option at one point, but she sees the way he looks at Kuriyama, and it’s so similar to the way Hiroomi looks at her that she can only hope for the best for them. She tells Hiroomi she loves him and kisses it into his skin, gives herself to him wholly. And when they are at school and he proclaims his love for little sisters and Akihito proclaims his love for glasses and the girls who wear them, Mitsuki lifts her nose in the air, sniffing and insulting, calling them perverts. But she is the pervert, the one who corners Hiroomi on the roof of school, the one who waits in his bed and inhales his smell when he’s gone.
That is where she is when he comes back from America, looking worn and exhausted. There had been a meeting he’d needed to attend, and she’d wanted to go but there must always be a Nase in town, and Izumi had been summoned as well, so she couldn’t.
Hiroomi doesn’t even seem to notice her at first, just tugs off his clothes and pulls on a pair of sleeping pants, slipping into the bed and burrowing under the blankets. It isn’t until he settles that he notices her staring at him, though he hardly seems surprised.
“I missed you, brother,” she murmurs, taking his wandering hand in her own and sliding forward, rubbing her nose against his. “Don’t leave for so long again.”
“Okay,” is Hiroomi’s tired reply, eyes already drooping shut. Mitsuki presses her lips to his, just a peck, and turns, bringing his arm around her body. He shuffles up close behind her, warm and solid and there and Mitsuki falls asleep to his heartbeat at her back.