Disclaimer: I don't own Naruto.

Kisame knew, very early on, that Itachi was not as he appeared. A thirteen year old boy, able to kill his entire family (aside from his younger brother) just to see what he was capable of? Maybe in Kirigakure that would have seemed plausible, but not in Konohagakure. No, there was something wrong with the story the young Uchiha had spun. What, he never found out, but he always knew that Itachi wasn't the cold-blooded killer he appeared to be.

For a start, he never killed unless it was necessary, and any deaths he did cause were always quick and relatively painless. Well, compared to those that met their end at the scales of Samehada, anyway. But that wasn't the only thing. Most murderers were proud of what they'd done – he himself never passed up an opportunity to recount some tale involving one of his many missions that had ended with his companions dead by his own hands – but Itachi refused to even hear mention of the impressive feat of killing (almost) the entire Uchiha clan by himself. And last, but definitely not least, were the nightmares.

If Kisame hadn't been watching his partner – if he hadn't spent enough missions sharing the same sleeping area, watching Itachi sleep and trusting Samehada to warn him of an attack – he would never have realised. But the signs, however subtle, were there. Itachi often perspired – only very slightly – as he slept, and on especially bad nights he might even shake a little. It was amazing how much control the teen had over his outward emotions, even as he slept. But even the genius of the Uchiha clan couldn't compose himself immediately upon waking. There was always the split-second hesitation as he realised where he was, as he extracted himself from his own hells, before the crimson Sharingan Kisame had come to know so well spun into existence. Again, only careful observations had revealed this lapse – to the casual observer it would appear as though he'd slept with his Sharingan active. Certainly when he closed his eyes to sleep it was the blazing crimson, not dull onyx, that was covered by his eyelids.

To begin with, Kisame didn't even know what colour Itachi's eyes really were. The Sharingan was always present, never switched off, even within the security of their hideouts. In fact, he'd started to think that maybe the rumours were false and that the Sharingan was the Uchiha clan's permanent eye state, before his observations had begun to reveal the hints of black the moment he awoke. Of course, nowadays Kisame was becoming somewhat more familiar with the deactivated state as Itachi's condition deteriorated and he became less able to keep it active the entire time.

The first time he had seen those black eyes, almost lifeless, he realised, it had shocked him so much he'd missed the other warning signs; Itachi's collapse was what was required to snap him back to reality. Slightly concerned, and definitely confused, he had picked up the slight teen and carried him the rest of the way to the nearest safe house, settling him down and watching over him until he awoke. Itachi's confusion wasn't as apparent as his own, but it was still there.

The second time the Sharingan had deactivated, Kisame also noticed the sight swaying of Itachi's body before the young Uchiha halted, hand on a tree for support. That time they'd been close enough for him to limp back to the hideout and settle himself down to sleep, but he'd only just beaten unconsciousness. That was when the first nagging feeling that something was wrong hit Kisame, but he pushed it aside, reasoning that Itachi knew what he was doing and the Sharingan obviously didn't take up much chakra so there was no real cause for concern.

It was the third time, after Orochimaru had defected and attempted something – Kisame wasn't sure on the details but he knew that it involved Itachi – and fled when it was unsuccessful, when Kisame realised an important clue. Each of Itachi's collapses had occurred soon after utilising the Mangekyo Sharingan. At that point, it was not a doujutsu that Itachi used much, so Kisame figured that he misjudged the amount of extra chakra it ate up. But still, the nagging feeling that there was more to it than just that wouldn't go away.

Then Itachi began to use the Mangekyo Sharingan more often, and suffered less. Kisame had noticed the extra stamina training his young partner had been doing and was pleased to realise that Itachi had reached the same conclusion that he had. During that time, the black eyes stayed concealed under their red guise. Kisame began to dread the black. From what he had gathered it signified that Itachi was completely out of chakra – a dangerous thing for any shinobi, no matter how powerful.

But the years went by and the black rarely showed itself. But when it did, it always heralded a collapse. Kisame noticed this and would always move to support Itachi when the Sharingan showed signs of fading, but the stubbornness of the Uchiha meant that Itachi never let him help, preferring to exhaust himself as they found the nearest place to rest. Kisame didn't like it, but he was scared of Itachi, and what Itachi would do to him if he persisted in attempting to help.

Eventually, the small cloak-and-dagger missions came to a halt and their Leader called a meeting. The grand plan was ready for fruition and they were all assigned their tasks. The Yonbi and the Kyuubi were their targets, although they would need to spend the next few years scouting before they could really move in for the kill, so to speak – they weren't actually allowed to kill their targets, just capture them. Kisame figured that they'd been given the Kyuubi because it was in Konoha, so Itachi would know best, and Kisame's own strength – assisted by Samehada – would help them win.

Then the news that Orochimaru had attacked Konoha and killed the Third Hokage filtered through to them and Itachi insisted on moving. Kisame wasn't happy – the Konoha shinobi had a fearsome reputation and wouldn't be pleased to see someone that was once their own – but Itachi wouldn't be denied and so they entered. Slipping past the barrier was simple and they soon stopped for a drink. It was the only time Itachi had deactivated his Sharingan willingly, but Kisame knew that it was to avoid standing out. After all, all those with the Kekkei Genkai were dead (Hatake Kakashi didn't count), or so he thought at the time. Itachi suddenly abandoned their drinks upon hearing something, but what Kisame didn't catch, and they walked away, back to the gates. They were stopped, and Itachi seemed almost glad for it as they fought the Jounin before escaping, the comforting red of the Sharingan (just because it wasn't the dull black that signified weakness) once again blazing fiercely. But he'd used Tsukiyomi, so Kisame was watchful. Itachi's stamina had increased so he wouldn't faint because of it, but he would still need to rest that evening.

But then they found the Kyuubi and it all went downhill from there because he was with none other than Jiraiya of the Sannin and not even Itachi could hope to defeat him. So they lured him away with a well-placed genjutsu on a young girl. But just as they were about to claim the young Jinchuuriki a problem emerged in the form of a young Itachi. The Sharingan blazed out of the young eyes, but unlike Itachi's, they didn't comfort Kisame. Instead, they filled him with dread, because the last time they'd faced a Sharingan Itachi had been forced to use his Tsukiyomi. Then he was told that it was Itachi's younger brother and that he wanted to kill Itachi. Itachi beat him using only taijutsu, for which Kisame was grateful for, but then something happened (he still doesn't know what) and Itachi used Tsukiyomi again. Now Kisame knew that the black was lurking just behind the red, threatening to engulf it in its void. The Sannin reappeared as they were once again about to depart with the Kyuubi and trapped them within a toad that could withstand everything they threw at it. Except Amaterasu. Now Kisame was really worried, as the black flames – he hated anything black if it was to do with Itachi – burnt them a hole to freedom and they fled. That meant that Itachi had used the Mangekyo Sharingan three times in one day – a feat he had never before accomplished. He watched as the red succumbed to the black and Itachi asked to find shelter. As Kisame feared, he didn't make it there before collapsing, leaving him to carry the too-light teenager (he was still a child, really) the rest of the way.

Everything went downhill from then on. Itachi began to cough up blood not much later and eventually admitted a fatal illness. From that point on, Kisame decided that even though he hated anything black to do with Itachi, he also hated the red – the red of the Sharingan that was destroying him and the red of the blood that erupted from his mouth all too frequently.

The years passed quickly and soon Itachi made his plans clear. He was dying – Kisame already knew that – but he wanted to be finished off by his little brother. From then on, although Kisame never learnt the truth, he knew enough to confirm his initial suspicions all those years ago that there was more to the story than Itachi let on.

He honoured Itachi's request to keep the little brother's platoon away while they fought, delighting in the chance to duel a fellow swordsman while he waited, and all too soon the news came that Itachi was dead. Before the body was disposed of, Kisame was allowed some time to say goodbye. He didn't, but he did look at the young man – he'd finally grown up – bathed in his own red and with those dull black eyes staring sightlessly past Kisame.

Kisame didn't stay long. He left, glad to be free of those colours of nightmare (but only when Itachi was involved, otherwise he loved them – the black of death and the red of freshly spilt blood) for the last time. Only then did he question himself.

When had he started caring?

Quick little thing I randomly thought of. There isn't enough fics about Itachi and Kisame (that don't involve romance) so I thought I'd add to the few there are. Sorry if the writing seems a bit off, it just came out that way.

I'm planning another one shot with these two shortly which hopefully I'll get up within the next 24 hours or so (oneshots don't normally take me long to write, especially not short ones like these), if anyone's interested (again, no romance).

Thanks for reading!

Tsari