Test subject A Prince of Tennis fan fiction
Kaidoh had outlived his usefulness as a test subject for the Inui juice.
Inui had come to this conclusion when he saw the other Seigaku regular running in the park. Inui had chosen his position and timing perfectly. When Kaidoh passed the tree he was sitting under his arm was outstretched with a thermos glinting ominously in the sunlight. He didn't even have to see Kaidoh startled at the sight of doom. This was routine - he could not even recall clearly how it all started, but there were memories of sun-drenched days in the park or by the river, making sure his kohai had enough air to breathe after dropping unconscious from the Inui juice he'd taken.
The other boy had turned a few shades of green at the sight of the thermos he was holding (it merely contained an innocuous vitamin drink he mixed) and Inui noted how he relaxed when he discovered it wasn't the dreaded new drink. He also noted that the pulse rate returned to normal at a 13.5 rate after the fear-induced increase, based on how the carotid artery pulsed under sun browned skin - Inui ought to put that down in his notebook, but his eyes strayed upwards, to Kaidoh's full lips as he drank, and stayed there for eleven seconds before he realized he was staring. He pushed up his glasses - thankfully opaque, and started to talk about their training menu even when his thoughts wandered elsewhere.
"Your stamina has again improved by 2.4 and - "
Kaidoh was developing resistance to the effects of the drink. His records showed that Kaidoh could take a drink that was now 12.45 stronger than the rest of the Regulars, with the exception of Fuji. (His theory of how the spicy food had capsaicin and isothiocyanates, which coated Fuji's stomach, letting him tolerate the drinks better that had yet to be tested.) And his fainting time after taking the Aozu was marginally longer as well - by 1.63 seconds. If this trend kept up Kaidoh would be resistant to his drinks in the long run, a thing that would be regarded with disfavor by the rest, citing favoritism. That Kaidoh had suffered all the while as his test subject would naturally not occur to them.
But Inui knew that Kaidoh had not truly outlived his usefulness as a test subject. He knew it was the worry he was starting to experience concerning his kohai. Any more and he might turn paranoid, start thinking Kaidoh regarded him as a monster rather than a sempai. And he truly didn't want Kaidoh to believe this was only for sadistic reasons. This was pure research, with Kaidoh as his first test subject. Scientists never fall for their test subjects, he thought, but what was happening to him now?
He decided to breach the idea while he helped Kaidoh warm down. Kaidoh would be unable to see his expression. He didn't bother to think that his hands would be on Kaidoh's back at that point. "Kaidoh," he said, getting the other boy's attention. Kaidoh glanced back, a feat of flexibility, since he was reaching for his toes. "On Thursday I have an experiment to undertake. I will not be bringing the usual then." 'The usual' was how they termed his experimental Inui juices.
Kaidoh breathed out - was that out of relief? - and asked, "Saturday, sempai?"
It would be best to suggest the possibility of a long discontinuance of this practice. "I might not finish with the experiments, but I trust you will continue on with the training menu we have just talked about."
"Yes, sempai," he said, obedient. Inui was just relieved Kaidoh had not sensed anything amiss.
Thursday. It had been more than a week since that conversation. Though Inui still saw Kaidoh during practice, he kept away from any interference with the other boy's training program. And though Kaidoh had once or twice raised the question of the Inui juice, he just smiled and said his experiment was taking longer than expected, and Kaidoh had not continued the inquiry further. And he did keep himself busy - looking for other ingredients for the juice (some of which entailed a thorough search for the edible members of the Class Insecta), hours in the library on new training regimen, spying on the other teams, studying for high school entrance exams, he had even taken up trying to get that lonesome snake plushie he happened to see in the arcade, just because it reminded him of someone.
So maybe there was no 'experiment', but he was noticeably absent from Kaidoh's training. He hadn't realized how much time he spent with his kohai until now, with the dearth of possible activities after practice to occupy him. He just wasn't - interested in any of these. Even making a more potent brew of Aozu held no appeal. Sure, he was spending part of his lunch break in the chemistry laboratory as always, but it was more of a habit rather than out of any pressing need. He had a stock of enough Inui juice variations to let the regulars live in pure terror for a month.
Inui wrote down a few more notes on the nutritional value of the new Inui juice, adding, as a whim, predicted reactions to it by the regulars of the tennis club, when someone knocked at the door of the laboratory. He stopped at midline, wondering if his teacher forgot something and came to open the door.
Kaidoh stood outside of the laboratory. "Sempai." There was something unusual in the timbre of the younger boy's voice that made him push his glasses higher on the bridge of his nose, to see what was wrong with his kohai.
"What is it, Kaidoh?" And if his voice came out a little higher than the usual, did it reflect his agitation at seeing Kaidoh here?
"Sempai, where is it?"
"Where is what?" he hedged. But Kaidoh knew of his habits as well. The latest variation was cooling on the counter. Kaidoh pushed him aside. It was the first time that had happened. When he reached the counter he gave a smoldering glance to Inui, as if he knew this was the reason why Inui had been avoiding him. "Ah, Kaidoh," he started, thinking to dissuade the boy from drinking. That was enough to make Kaidoh grab the glass and -
He drank. He drank it till the last drop clung precariously on the glass' rim. Inui watched him, surprised behind his glasses. He'd always thought that Kaidoh believed the drink was poison, and would try to avoid it as much as possible. A part of him observed Kaidoh's reaction with detachment. Kaidoh was not turning ill so far, which was a bad sign. Maybe he should have added more -
Kaidoh grabbed him by his shirt. "Kai - " And then his kohai's lips were against his, and the faint taste of the juice marred the heat of their kiss. Inui could taste the faint remnants of shichimi Kaidoh had mixed in his udon as he swiped his tongue over the other boy's lips, before delving deeper into that mouth. It was Kaidoh who broke away first, flushed.
The look Kaidoh gave him could be misconstrued as a pout, Inui managed to think, still dazed. "Saturday," Kaidoh said. Inui was still trying to think why Kaidoh would kiss him, because the only reason he could think was that it had not been one-sided, all this while, and the worry he was experiencing was reciprocation in Kaidoh's caring for him a little bit more than expected.
"What about Saturday?"
"You've missed three days, sempai. I - I think I need your advice concerning my training." His annoyance spent, he let go of his sempai's shirt. Ah, back to his hesitant self apparently, Inui thought. Kaidoh's body language revealed the nuances of his thoughts, amazement that he kissed his sempai, angry with himself for being so forward, and doubt for what? Doubt that Inui didn't understand what this was all about?
Inui wasn't certain himself, but he was willing to let this go on. "I can go later - sans thermos, apparently." He lifted a hand to smooth Kaidoh's hair, stopped it in midair while he hesitated, unsure of Kaidoh's reaction. "I don't think we'll need the excuse of the Inui juice anymore," he said.
"Good." And Kaidoh's expression gave Inui enough reassurance to lift his kohai's face up for another kiss.
-end Test Subject-
One of the few fanfics I've actually finished in a long time. For the birthday girl, AAincognito, maker of the InuKai notes!