Author notes: I do not own Naruto, if I did, these two would get waaaay more screentime.

This is slash. It involves Kisame and Itachi.

Compared to Kisame, Itachi is small. It's not something that the large nin notices all that often; to him, most everyone is small with the possible exception of some of the Stone's larger taijutsu masters. It's only when Itachi does something to accentuate his smaller stature that the realisation of his partner's diminutive form really hits home for the Mist nin. Kisame doesn't want to refer to Itachi as doll-like, with his slender frame and bird-bone lightness, because the last thing he wants to do is imply that the Uchiha is weak. There is not a single fibre, either bone, muscle or chakra, of an inadequate nature in any part of the youth's body. At least, none that Kisame has ever seen.

It's at times like this though, where Kisame rests on one knee and dips his head to look into the low opening that Itachi has wedged himself into, that he feels the difference between their sizes the most keenly. He squints uncertainly, trying to force his eyes to adjust to the gloom under the craggy outcropping, and looks for the shine of Itachi's eyes in the darkness. There, at the back, far out of reach. Kisame shifts uncomfortably, resting one hand on the top lip of the opening and leans his head a little further into the low cave.

"Itachi-san," he inquires politely, "What are you doing?"

He is met with silence from the back of the cave and the slow, steady drip of water somewhere off to one side. His outward show of calm indifference is one that he has practised especially for times such as these. Masks for a ninja, should be as varied and easy to slip on as the paper masks of the summer festivals. With Itachi, Kisame has learnt that the best mask is often indifference. With genius comes madness they say, but then, Kisame supposes that they are all mad, if only a little. Except for him. He is perfectly fine, of that he is quite certain.

He waits a few more minutes, as long as he dares, not quite willing to risk his partner's ire by repeating the question, before flicking an eyebrow and rising to his feet, dusting off his cloak with his palms.

"I have secured us a room at the Sailing Lotus. It's on the corner of the main street, by the bakery. Second floor, room eight."

He waits. No answer. Kisame sighs quietly and sets off back through the forest to the town below.

Over the years he has been working with the Uchiha prodigy, Kisame has become accustomed to the occasional runs of mental instability that accompany the gift of genius. Throughout his career as a shinobi, the Mist nin has met many gifted, exceptional or just plain eccentric ninja, but even he has to admit, he has never quite met anyone with the same emotional edge that Itachi possesses. Or rather, it's more like the complete lack of an emotional edge. During their partnership, Kisame has seen the full range of Itachi moods, from silent, deadly calm, through silent, deadly interest, to silent, deadly rage. He's been on the receiving end of most of them, except perhaps for the silent, deadly rage. Kisame is man enough to admit to himself, if not anyone else, that should the Uchiha turn his rage and his Sharingan gaze upon his partner, then it is most likely that there will be but the one of them walking away from the encounter with any sanity remaining. He thinks about that for a while as he lies on his back and stares blankly up at the ceiling of the inn. It is not, he concludes, at all certain if that thought should not have read more along the lines of "any such encounter would result in the last of the partnership's quota of sanity being completely eradicated." Somehow he thinks, that feels more accurate.

It is not that Itachi is a raving lunatic; the youth is beyond such petty things as ranting in the streets, insane laughter or diabolical master plans (although Kisame has to admit, such things would be a welcome break from the actual manner in which Itachi does manifest his insanity). Itachi's madness, if it can even be referred to as such, is in his inability to comprehend emotions and emotional consequences, leading to his almost total disconnection from the rest of Humanity. Itachi simply does not think like other human beings. He lacks the ability to empathise, and the subsequent methods of his existence are often contrary to everything held dear by the average person on the street.

Because he does not comprehend emotional consequence or such effects his actions have on his victims, he has no need of guilt. Kisame would say that his partner lacks even the ability to feel such an emotion, but sometimes, just barely, there is something that might be a flicker of a reaction, a hidden edge of emotion usually distant behind those moody red eyes brought suddenly, inexplicably to the surface. It's times like that which truly frighten Kisame. It's at times like that he knows he should be either running for cover or positioning himself at the Uchiha's side where he can avoid the worst of the blast radius by being there to help it on its way.

And then there's the times that Itachi just loses himself completely. They're rare, and mostly harmless, and Kisame has next to no idea, even after all these years of working with the boy, exactly what it is that sets them off. During these times the person looking out at him from behind those Sharingan eyes is not the same person that walks the lands beside him, cuts down their prey with his sword and his jutsus, or furthers the goals of the Akatsuki through blood, death, fear and manipulation. This person looks back at him and through him and does not see him at all. This person sits alone and whispers to himself words that are too low for Kisame to hear. Not that he has ever tried too hard to discern the words; somehow Kisame is quite certain he doesn't really want to know.

Over the years, Hoshigaki Kisame has perfected the art of simply overlooking the rare occasions where his partner's outward veneer of polite normalcy slips and the veil of his sanity grows a little thin. Those times where Itachi's hands grip his sake cup so tightly that it cracks and breaks, driving splinters of pottery into his fingers and sending droplets of fine blood to the tabletop. It is better not to listen to the boy whispering into the dark because if you just wait long enough, his eyes will lose that stark look and slowly relax back from their whirling red and black to the gentle stationary resting state of the activated Sharingan. And to be fair to his partner, these incidents don't happen often and when they do, they're mostly short-lived.

It is well past midnight when he feels the whisper of Itachi's chakra in the corridor outside the room and immediately he rolls over in the bed onto his side, lowering his breathing and slowing his heartbeat to imitate sleep. He doesn't know why he does it, but perhaps it is because he does not wish to provoke the Uchiha's displeasure by looking like some doting mother waiting up for her errant child. The thought puts a self-deprecatory scowl on his face that is still there when the door creaks open and Itachi makes his way into the darkness of the room.

The nin makes no sound as he crosses the small bedroom and Kisame tracks him by only the barest whisper of a chakra signature, apparent only to one so very familiar with him for such an extended period of years. He listens in silence for the sounds of the heavy cloak being removed, its buttons popping almost too loudly in the quiet room. He measures his breathing by the folding of the garment over a chair, the chink of a kunai holster on the floorboards beside the bed and the soft creak and lowering of the mattress as Itachi puts his weight on it and moves towards him. Kisame waits quietly as the youth slips beneath the covers of the bed and stretches himself out beside his partner.

For a long while there is nothing but the barely perceptible sound of them both breathing and Kisame has just begun to allow himself to drift off to sleep when Itachi shifts abruptly onto his side and rakes his nails down Kisame's back.

Ah? I see...Kisame thinks to himself and cannot help the grin that stretches his lips into something akin to a snarl. He makes a low noise of protest in his throat because that is what is expected, no, desired of him and rolls onto his back, turning his face towards where he knows the other is watching him. Hands trail down his chest, nails scraping over tough blue skin, catching on his ribs and moving lower to do things that make Kisame's breath hiss through suddenly clenched teeth.

He knows what the Uchiha desires, they have played this game enough times in the past for him to read the exact request in the touch of his partner's hands, in the way they pull him down and pretend to threaten all at once, only to slip away and back when Kisame finally gives him what he wants and moves to lie on top of him.

It's always hard to tell exactly how far Itachi wants to go on these occasions. Kisame has learnt to read the youth's moods better than any other alive, but these rare times when Itachi lets his grip on both his sanity and his morals slip are so infrequent that he is forced to do more guesswork than he feels strictly confidant doing. After all, he is engaging in acts of a dubious nature with one of the most powerful, dangerous and currently downright unpredictable shinobi in all the Countries. Itachi is a psychopath, plain and simple, and even Kisame must ensure not to provoke him too indifferently.

So he lets Itachi guide him with his nails and his teeth and the grip of his arms around his shoulders. It is at times like this that Kisame appreciates just how small the other man is in comparison to him. From the way they have played this little game of submission and domination both now and before, Kisame supposes that Itachi gets a kick out of the difference in their size. He would analyse the thought further, but the youth is shifting beneath him, pressing against him in the most distracting way and it is a far more interesting prospect to reach down and sink his teeth into the boy's shoulder and feel his whole body jerk in response.

It is not until sometime later with Itachi pressing back against his thighs, gasping and trembling, the sheer embodiment of heat and need, that Kisame wonders if this is perhaps the only way, outside of torturing his younger brother, that the boy can confirm that he is in fact a part of the human race. This contrary willing submission being the only way that he knows how to manifest any vague resemblance to a guilty conscience, the only punishment explored being the one whereby he accepts that perhaps, just possibly, he too has limits.

Itachi hisses suddenly and stiffens against him, arching back against his chest, Sharingan eyes momentarily unseeing. Kisame holds him through it, fascinated and entranced by his own lust and isn't surprised when moments later when both their breathing has slowed, Itachi twists and with an elbow below the ribs, shoves his partner to one side and away from him.

Kisame does not bother protesting, nor pursuing, nor sulking. Instead he stretches in satisfaction as Itachi moves away and out from under the covers, stooping to pick up the kunai holster from the floor before making his way over to the room's other single bed. If they are to remain loyal to previous episodes, Itachi will climb into his bed, settle himself and fall asleep leaving Kisame to spend the first part of the night watching over them both until his partner reawakens for his own turn. But Kisame has been thinking tonight, something that has always gotten him into more trouble than he can reasonably handle alone, and so instead of doing the wise thing and allowing Itachi to sleep, he lets his curiosity get the better of him.

"Itachi-san," he says thoughtfully, amiably. "What exactly were you doing in that cave?"

As soon as the words leave his lips he thinks them a mistake. There is, after all, only so far one can push the Uchiha prodigy before he pushes right back; harder, sharper and faster than Kisame ever could. Without realising it, he holds his breath as he listens to his partner shift, pause and then, after a long, tense moment, settle again without answering.

In the dark, Kisame relaxes and lets out the breath he hadn't realised he was holding. Perhaps it's better that he does not get an answer, he thinks. There is, after all, only so much contact with Itachi's unique brand of sanity that he thinks he can cope with handling.

Kisame for one, certainly knows his own limits.