A/N: prompt from zenellyraen: KuraHi: "You're jealous, aren't you?"

Hot and Cold

Kurama wasn't sure what had prompted the first visits to Yukina, where she stayed at Genkai's complex.

No. That wasn't quite true. He knew the reasons, though they were so numerous and varied that he could never attribute it to just one. Then again, that was how he operated. Always more motivations behind his moves than he would let on. Perhaps that was what made simple, straightforward Yusuke wary of him—that he couldn't grasp the deeper reasoning that drove Kurama.

Protectiveness was one-never mind that Yukina and Genkai were perfectly capable of taking care of themselves—but then of course, there was kindness, offering the presence of another familiar face, another being who had experience in both the human and demon world, for her sake. These two inclinations certainly had prompted the first visits. And then it had quickly become a habit. In a way, it was a part of his territory, though he had never thought of Yukina as a thing, in fact, he'd grown to appreciate her warm personality as much as his human mother's. Had come to recognize her as family.

And there was the other reason, then.

Hiei was often nearby. Kurama could sense him, a fiery presence, one that he would've recognized anywhere. He would be in a tree, watching, listening. Or, if he wasn't close enough to have a direct line of sight, Kurama knew Hiei would make use of his Jagan eye. After all, that had the purpose of having the implant, in the first place.

Kurama was fairly certain that it was only stubbornness that prevented Hiei for revealing himself as Yukina's brother to her, at this point. She'd never shown him anything but the same quiet cheerfulness that she had for all of their group, even despite Hiei's proclivity for coldness—one that Kurama knew well to be little more than a facade. A thick one, but a facade nonetheless.

Still. With Hiei silent on the matter—and demanding silence from the few of them that knew—Kurama felt that Yukina deserved at least some kind of bond with her family, even if it was an invisible one. So he'd chosen to act as an impromptu bridge between the two: his visits with Yukina bringing her closer to Hiei, through Kurama.

She didn't know it, but she and Kurama were practically family, anyway.

Kurama found that Yukina's bright inquisitiveness and intelligence made her excellent company. She even asked after his methods of fighting, and the best way to defend different types of attacks-the question had been surprising, at first, considering her gentle nature, but then, given her track record, and the people that surrounded her, he should've expected it sooner.

And, Kurama realized, that though Yukina had Genkai to refer to, Yukina was still, in effect, his pupil. He couldn't recall a time, in recent memory, that he'd taken on a pupil. But Yukina was willing to learn, and he was happy to teach.

Kurama began to notice a pattern, though, on the days that he and Yukina discussed fighting strategies and the use of one's terrain. Hiei, in his tree, would narrow his eyes. Sometimes he would leave altogether, and whenever Kurama would next see him, he would be seething with rage, more cold and curt than usual.

Kurama spared him a raised eyebrow, occasionally met the narrowed red eyes with a pair of green, but knew that Hiei would address whatever issue he had with Kurama in his own time.

And he did, eventually.

Kurama was a block away from his apartment building when he caught the scent on the air, felt the spark of heat somewhere in the vicinity of his flat. It wasn't so unusual, for Hiei to visit his flat, in fact, Kurama thought that it was one of the few places Hiei would stay for more than a handful of hours at a time. But he'd just come from Genkai's complex, another lesson with Yukina, and Hiei always avoided him directly after those.

He took a breath as he stepped into the elevator, preparing for a fight—not a physical one, rather a battle of words and wit. Truthfully, though Hiei was clever, the challenge would come from his sour mood, rather than a logical argument.

Hiei was half-sitting on the open windowsill when Kurama unlocked his door and let it swing open. Of course he'd used the window, never mind that Kurama's flat was halfway up a mid-rise building, never mind that there was a door, and despite Kurama's constant requests that he use the door.

Kurama supposed that at least he hadn't broken the lock this way, though it riled, a little, that Hiei had intruded without announcement, and in such a mood.

Kurama pointedly ignored Hiei as he set his bag down, hung his coat, made himself comfortable. He lit the stove for tea, and only as he was pulling out a mug for his tea did he look at Hiei, who was staring at him darkly.

"Tea?" He said it lightly, amicably, despite the irritation clear on the other's face.

"Tch." Hiei's eyes slid to the side. Of course. Kurama pulled a second mug and set it next to the first, anyway.

Silence settled between them as the kettle warmed, and then boiled, Kurama preparing tea as if he didn't notice the tension defining the set of Hiei's shoulders. Pouring two mugs, taking one for himself, and leaving the other for Hiei to take, if he wanted.

Of course Hiei didn't. Instead, he finally opened his mouth, avoiding Kurama's eyes. "You're wasting your time with Yukina. She doesn't need your help."

"Hiei," Kurama chided, "she asked."

Hiei glowered. "Then you should teach her better. You're even worse at demonstrating techniques than that old hag."

Kurama raised an eyebrow as he sipped at his tea. Softly: "I hardly think you're one to talk. If you think you could do better, then go train her yourself." Then, a little teasing, "Maybe help her search for her long-lost brother, while you're at it."

Hiei's eyes spoke of murder.

Kurama watched Hiei over his mug, eyes flicking from the tightness of his muscles, to the micro-expressions of his face. A thought crossed his mind, and as it did, he took hold of it, and wondered why he hadn't realized earlier. "You're jealous, aren't you?"

Hiei glared at him a moment longer, before his eyes found somewhere else to rest.

Jealousy, in Hiei. Kurama found this thought both endearing and amusing, and couldn't help the small chuckle that bubbled out of his mouth.

Hiei's gaze swung back, piercing, as if Kurama could be intimidated by a look. His voice came out sharp. "Why are you laughing? Stupid fox, what would I be jealous of? I don't think—"

Kurama cut him off with an amused, "Oh, Hiei. Really. If you're going to be stubborn on the matter, then you've no right to be jealous, as well. You know, you could train with her, without revealing your identity."

"She's not interested in me."

Kurama let out a small hum. "I think you don't give her enough credit."

"Tch. What do you know?"

Gently, "A good deal more than you. Even if you're always watching, there's things you learn about a person by being close." Kurama placed his unfinished tea on the counter, and stepped towards Hiei. "And that is why you are jealous."

Hiei shifted at Kurama's approach. Not quite into a fighting stance, because the quarters were too close, and really, Kurama wasn't threatening him, but he wasn't happy, and he wanted to make it known. Not that that had ever stopped Kurama.

"Hiei." Kurama closed the distance between them, tilting Hiei's face up with a hand on his jaw, and let out a small sigh. "Whether you'll admit it or not, Yukina is your sister." Hiei scowled. "And whether she knows it or not, that still makes her family to me, too."

Hiei's scowl deepened, but, Kurama noted, he didn't pull away from Kurama's caress. He allowed the affectionate hand in his hair. Kurama felt a sly smile spread across his lips when Hiei cut his eyes away again, a faint flush on his cheeks.