He thought it was beautiful, because he didn't understand.
Hayate isn't exactly small-framed, but his wrists and his face and his chest are all so thin you can feel the bones with the slightest touch. Genma thought it was a beautiful and delicate look when he first saw the boy. He didn't know that where there should have been child-fat or at least muscle, disease had eaten away until it was only sallow skin wrapped around bone. He didn't know that late at night, Hayate sat up in bed and coughed until it bled and prayed for the pain to stop, and didn't care if he was beautiful or hideous or if anyone even saw him at all.
They spoke twice, shy boys who didn't care how far apart their ages were, practicing to be teenagers who teased and flirted and didn't know what they wanted. Their words were simple, Genma showing off his shuriken, and Hayate smiling demurely, the corners of his mouth not-quite-turned-up. He seemed uncertain of whether to be friendly, as though Genma was mocking him. Over sparring practice, their eyes didn't quite meet, but Genma brought him lunch and they ate silently.
It was always like that, an uneasy quiet between them. Genma didn't try to get the softspoken boy to say more than he wanted to, and Hayate seemed happier just listening to his sole companion's loud, meaningless chatter or contemplative pauses.
Summers seemed to stretch on forever, blending with one another, and then with a suddenness that wasted all which had gone before, they were both adolescents, stumbling over ungainly limbs that had grown too fast, and exchanging rushed, groping kisses in the weapons shed or behind the Academy.
Now Hayate did think of his body, of its thinness that was edging on being unattractive, more than he seemed to focus on anything else. His hormones told him he wanted to be loved, and the full-length mirror in his bedroom told him he'd have to try hard before that was going to happen. And meanwhile they continued to fumble around, with no guidance and none of their own idea of what they were doing.
Genma didn't see any of that, because Hayate pointedly kept their time together to only training, so that his parents wouldn't suspect anything. But there were a lot of things Genma didn't see. He didn't notice that Hayate always turned out the lights before they moved into a session of caresses or sloppy (but growing gradually more graceful) kissing. He didn't see that, the few times he actually saw Hayate naked without his body being just another, more darkly smudged-out shadow in a dark room, the ridges of Hayate's ribs stood distinct framing the smooth plane of his pale stomach.
He saw a friend, a lover, who to him could be nothing but perfect. And to Genma, nothing could ever be wrong.
Genma never worried about hurting Hayate, and was always as rough or as gentle as he felt he should be, and Hayate never complained. At some point after a mission that left Hayate near-dead and in the hospital for several weeks, they had realized the transience of their paradise, and things began to move faster. Kisses and shy touches metamorphosed into tangled bodies trying to find a way to fit closer together, always closer. It went beyond anything they had ever realized they could achieve; and it didn't go far enough to give them quite the closeness they desired.
It was a hidden thing. It felt like a dirty secret, no matter how pure the act itself ever seemed. Genma hated being dishonest.
Life swept along, bringing them with it, unwillingly. Their childhoods had ended; they were growing into adults, who would not bend as easily to taboos. But there began to grow between them a sense of an ending, of something greater than themselves which they could not surpass.
It ended much more suddenly than it had begun: a series of fights over four days and then there was nothing left. Hayate said Genma was too old for him. Hayate said Genma was a good person, but it couldn't work out. Genma said, 'Fine. Leave.'
But Genma never said he was sorry.
It was two years until they saw each other again. Genma had finally succeeded in his goal of becoming an instructor at the academy; Hayate was standing at the front desk with a purple-haired woman when he walked by on his way to class.
The dark-haired shinobi looked paler, gaunt. Genma commented. Hayate coughed self-consciously and said he was feeling well, though. The woman stared at Genma as though trying to place him.
To fill the awkward silence, Hayate explained that he was there to accept a position as Chuunin exam proctor. Genma hugged him and said it was good to see him again, see that he was finally doing something with his life. And all the while, he was trying not to focus on the fact that even through the padding of both their vests, he could feel the press of Hayate's ribcage; that when they shook hands the wrist that protruded from a navy blue sleeve is skeletally thin. It's hard not to notice things when you're thinking about ignoring them.
Sometime afterward, Genma is thinking about Hayate again, and the feel of his thinness and cold fingertips. Those were the best days, he realizes, when he thought it was beautiful and delicate, when he was too young to know otherwise. Anymore, the beauty seems melancholy, and everything delicate is only fragile. He was finally seeing Hayate, and now, it didn't make his heart soar.
It only made him sad.