A/N: Set directly after the Dark Tournament. Because this popped into my head in the shower and throttled my brain and made me snort, and it actually made sense. It's a stand-alone oneshot; just in here because it's Hiei and Kurama.
'Answer me a question,' Hiei said on the way back to Kurama's house.
The ship had docked at an unearthly hour, and the streets were deserted as they moved silently through them. Kurama looked rather happy to go home, and had invited Hiei to spend the night at his place, since they could both use a good night's sleep without worrying about intruders; no youkai around the city was stupid enough to attack them when they were together. Hiei had accepted; he was more tired than he appeared, and at least staying with Kurama meant three square meals, clean clothes and privacy, which was more than a tree could provide.
'Hmm?' Kurama said absently. He was tossing his keys up into the air and catching them soundlessly as he walked. Since the key ring was full of keys and would, in anyone else's hands, have clanked abominably each time they connected with their palm, this was an impressive feat.
'There's something strange,' Hiei said slowly, 'about your transformations.'
Clank.
'Er,' Kurama said. 'Yes?'
'Youkai transformation is usually very quick,' Hiei pointed out. This was something they both knew well – any situation that required a youkai to transform into their most powerful form was one that didn't permit shilly-shallying. 'And usually not as flashy as yours is. All that smoke and crackling youki. It's very impressive, I'll admit, but there isn't any point to it. Is it a side-effect of the potion?'
'….something like that,' Kurama said, scrubbing at the back of his head.
'Liar.'
'Ah. Well. No, not really a side effect. Although you could say it was, too.'
Hiei shot him a speaking look. 'I am not stupid. 'It takes less than a second for youki to change from one to the other; so there's a reason for the special effects. You're hiding something, fox. Out with it.'
His eyebrow then shot up. Kurama was, of all things…blushing.
'Now,' he said slowly, 'I'm really curious.'
'…do we really have to discuss this?' Kurama asked plaintively.
'You owe me,' Hiei snapped.
Kurama sighed. 'Hiei? Rest assured that if Yusuke, Kuwabara or anyone else ever hears about this, I will feel the need to exact revenge.'
Hiei grunted. 'Stop delaying.'
'…the time,' Kurama mumbled.
'What?'
'The potion. It's not effective enough, so it takes a little longer than it should to transform me from half-human to full youkai; there's a gap of about fifteen seconds. That's why I need the protection of that smoke.'
'Protection?' Hiei asked, puzzled.
Kurama looked embarrassed. 'There's one major difference between your transformation and mine.'
'And that is?' Hiei asked. He was getting a little tired of all the deflecting.
'Well, when you transform…your clothes stay the same.' Kurama shrugged, still a little pink around the cheeks. 'Mine, on the other hand…'
It took him a second to get it, and a few more to double-check the information.
'…ah,' Hiei said finally, enlightened. He fought valiantly to keep a straight face, because he was in no condition to fight, and if he even cracked a grin, Kurama would have him chopped into mincemeat to feed one or the other of those really creepy plants he carried in his forelocks.
'So you see,' Kurama said, sounding composed again, and not at all like someone who had come within seconds of flashing an entire arena of youkai, including at least one who had had an entirely unhealthy fixation on him, 'that was why I sent all that smoke flying around; you were right, by the way; I was the one who generated the smoke. I thought it was rather well done, myself. Elegant, but dramatic; understated, but effective.'
'…I see,' Hiei said, too numb to even make a comment on Kurama's vanity. He was still fighting that attack of laughter, which threatened to overwhelm him at any second.
'It's only the potion that's delaying the transformation,' Kurama said thoughtfully. 'If I can bring myself to the point where I can transform without artificial catalysts, I can deal with that problem quite easily.'
Hiei said nothing for a while, and they walked along in silence.
'I suppose I should get to practicing the transformation,' Kurama said, eyeing him sideways, with That Look in his eyes.
'How do you suppose you're going to record the time?' Hiei inquired.
'Why, are you volunteering?'
Hiei choked.