Over the course of the next two months, Kisame couldn't help but dwell on his partner's refusal to leave him behind on their disastrous retrieval mission. He knew that it was pointless to think about it; nobody in the entire Akatsuki had the mental faculties to comprehend the inner workings of Itachi's mind, so even if Kisame devoted every waking moment of his day to thinking about his partner's motivation or logic, he'd only end up exactly where he'd started. He didn't dare try to bring up the topic with Itachi after their last fight, and the Uchiha himself seemed to be acting completely normal once again. So no matter how one looked at it, it was completely pointless for Kisame to get so hung up on this single faux pas of ninja protocol. Every fiber of his being was telling him to just let it go and be grateful that he was still alive and moving; but he couldn't. He just couldn't.
After accepting that he'd never get a straight answer, Kisame had decided to quietly observe Itachi over the next few assignments to see if he could gain any new insight into the psyche of his partner. Maybe Itachi had a secret soft side that liked caring for wounded animals, and it happened to carry over to taking care of injured partners. Maybe the weasel felt like he owed Kisame for some past favor the shark had done, or else was planning on earning a favor by saving Kisame then (not happening, if that was the case). There had to be some explanation; Kisame just needed to find it.
But no answers were forthcoming, and analyzing his partner revealed no new information; if anything, it just succeeded in making Kisame's life more difficult when Itachi grew annoyed at the shark following him everywhere. And then, several months after that fateful day, on an entirely different mission, things officially went to shit.
A possible lead on the location of a tailed beast had turned out to be a false tip with a fair number of deadly ninjas lying in wait for them in a field; further complicating the matter, on top of the usual grunts in the party, several of the enemies were genjutsu masters. Kisame, to his credit, was overall fairly adept at handling genjutsu users on normal assignments, usually by removing their head from the rest of their body after breaking through their genjutsus. These ninjas, however, were quite good at layering illusion upon illusion, and Kisame no sooner broke through one hallucination than another appeared before his eyes. "Oh give me a fucking break," he growled after bursting through an illusion of an ocean only to find himself in the middle of a never-ending hallway. He wouldn't be able to keep this up forever; besides, there was no telling how long his physical body back in the real world would last as he tried to break his mind free from their control.
All of a sudden the hallway disappeared and Kisame found himself back in the middle of the field he and Itachi had encountered the enemies in. He was now surrounded by a number of ninjas that were either incapacitated or on fire; Itachi must have taken care of them while his partner was trapped in the illusionary world. Speaking of whom…
Kisame looked around until he finally located a clearly exhausted Itachi kneeling on the ground and panting to catch his breath. That in and of itself wasn't a good sign; for Itachi to be winded like this was highly irregular. He was bleeding from a large gash on his leg as well, which was quickly soaking through the fabric of his pants; even more worrisome. "What the hell happened to you?" Kisame asked, studying his injured partner with more curiosity than worry.
Itachi glared up at the shark as he shakily rose to his feet. "We were attacked," he explained.
"That's not…oh forget it," Kisame grumbled with a dismissive wave of his hand. It didn't really matter what specifically had happened to his partner, and surprise surprise, Itachi didn't feel like telling him what had transpired while the shark was incapacitated. "Look, we need to get out of here. We're pretty much in the middle of nowhere, but when these guys don't show up again at their base we're going to have some of their friends chasing us down. I'd say we have maybe a day's head start before company joins us."
"Hn," Itachi agreed. "We need to go."
The two ninjas set off as quickly as their injuries would allow; Kisame only had a few scratches compared to Itachi's gaping leg wound, but breaking through all those illusions had taken a rather heavy toll on his chakra supply, massive though it was. Progress was slow, though Kisame was convinced it would have been a bit less so if Itachi wasn't so badly injured. Eventually they had to stop on the side of the road so Itachi could give his wound a proper bandage job when the hurried field wrap began to come undone. "Hurry up," Kisame ordered. "Or I'm leaving." Itachi said nothing, choosing instead to focus on wrapping his leg. Once he was convinced that the bandage would hold, the two were off again hobbling as quickly as they could, out of the field and into a forest that would at least provide them with a bit of cover.
They spent nearly half a day like this, with Kisame growing progressively more and more annoyed at his partner. The kid's injury was going to cost them any head start they might have otherwise gained, and if the first line of attack had such powerful genjutsu users, Kisame really didn't want to see what kind of power and abilities the reinforcements were packing. Finally, when Itachi insisted that they pull over and take shelter in an old hunter's lodge, Kisame had had enough. "We're going to get killed if we keep going this slowly!" he snapped.
Itachi shook his head as he rewrapped his bandages once again. "I need some time to rest."
"Well fine, take all the time you need. I'm heading back to the base," Kisame declared as he stormed across the single room of the hut towards the exit. He opened the door, paused, curtly said, "I'll try and lead them off your trail," and then slammed the door shut behind him.
Free of the burden of an injured ally, Kisame was able to travel at a much faster pace and quickly put a safe distance between himself and the battlefield. Yet even as he traveled, the feeling of annoyance brought on by Itachi's injuries didn't subside. If anything, his frustration grew with each step he took; soon, his stupid brain was thinking about his own injuries from that fight not so long ago, and how Itachi had stuck with him then. "That was a stupid move then, and it's a stupid move now," Kisame told himself. "He's just lucky we weren't caught."
Kisame kept sprinting through the woods.
"Really stupid. It went against every aspect of training we've received since day one."
The sprinting slowed to an easy run.
"No one else would've done that, because they know better! Tch, and people call him a genius."
The run slowed to a fast walk.
"I never would have done that. Not as a rookie, not as a squad leader, not with any of my old partners. Seriously, what the hell was he thinking…"
The walk slowed and then stopped.
"God fucking damnit!" Kisame swore as he spun around and charged back the way he came, cursing Itachi all the while. "Why did that stupid brat have to go crazy on me?!"
Kisame's head start was completely destroyed as he backtracked towards the hunter's cabin; the odds were very much against him and Itachi being able to escape their pursuers now. Needless to say, Kisame was not very happy to discover the several layers of genjutsu that Itachi had tacked onto his hideout, and probably ripped through them with more force than was strictly necessary. He entered the cabin to find a very dazed Itachi slumped over on the floor taking shaky breaths; yeah, definitely more force than was necessary. "Stupid crazy pain in the ass kid," he snarled as he kneeled down and scooped up Itachi in his arms before the Uchiha knew what was happening. "I ought to just snap your neck now," he went on as he stormed out of the cabin and took off into the forest once more.
"Thought you said…you could carry me with one arm," Itachi whispered.
"You're lucky I'm not dragging you along by your hair," Kisame growled. "And between you and Samehada, I'm packing an easy 200 pounds here, so stuff it!" Itachi listened to his partner and didn't reply, allowing himself to be carried in silence.
Unfortunately for both of them, Kisame's predictions were right; the next day their enemies were able to catch up. Twice he had to stop and hide Itachi in the thick bushes growing near the base of a great tree, telling the Uchiha to stay put until he got back, and twice he had to return and retrieve his still feeble partner after the other ninjas had either been led off their trail or worse. Their only saving grace was that these reinforcements relied quite heavily on brute force; and in a contest of pure strength, there was no beating the Hoshigaki. That didn't mean fighting off the attackers was easy, oh no, not by any stretch of the imagination; it merely meant that such a task was not completely impossible.
"Should've just left you back there," the shark growled after he picked up Itachi for the second time. "Should've just gone back to the base myself, damnit." Itachi tried not to take the grumbling personally, seeing as Kisame was looking pretty beat up by now, and he of course had the good sense not to mention the swordsman's weakened state aloud. They were traveling along a river now; in his frustration, the shark might legitimately try to drown him. Instead, he shut his eyes and leaned his head against Kisame's chest, trying to doze if he couldn't completely fall asleep.
After a few more days, the two Akatsuki members had either managed to completely elude their pursuers or said pursuers had given up on hunting them down. Itachi had mostly recovered by this point, by his leg wound prevented him from moving at any pace faster than a slight jog. Several times Kisame grew frustrated enough by this to loop the Uchiha's arm over his shoulder to half-carry the weasel along with him, cursing all the while. "Seriously, this is never going to happen again," he promised Itachi in a grumble.
"Hn," Itachi murmured softly.
"And what's that supposed to mean?"
Itachi tilted his head up to look Kisame in the eye. "Thank you for this once, then."
The shark made a noise of disgust and turned his head away. "Whatever."
Unlike Kisame's burn, their wounds from this debacle didn't require immediate attention. They hurried along and passed through several villages with sufficient means to patch them up, choosing instead to wait until they were in the village near the mountainside base to receive proper medical treatment. The doctors here knew better than to ask any questions more intrusive than, "How old is this?" or "Are you absolutely certain you weren't poisoned?" A couple stitches for Itachi, a little salve for Kisame's scrapes, and the two of them were on their way before the afternoon was out.
The report to Pein was mostly factual, and concerned itself almost entirely with the betrayal to the Akatsuki and recommended acts of retribution against the local priest that had fed them the misinformation in the first place. At no point was Itachi's weakened state brought up, nor Kisame's efforts to get the weasel back to the base. As far as Pein knew, they'd both successfully escaped with only minor injuries and had taken out quite a few enemy ninjas in the process. They were both commended for a job well done and then dismissed to await further orders.
Neither Kisame nor Itachi spoke on the way out of the office, nor did they talk in the hallway on the way to their room. It wasn't until they were both in the bedroom with the door locked behind them that Kisame said anything. "Don't expect me to ever do that again," he stated firmly. "That was a one-time error in judgment, got it?"
"So you've said," was all Itachi replied as he reached his bed and stretched out, clearly exhausted from the past several days.
Kisame rolled his eyes at the weasel's answer. "I told you I'd leave you behind, and I meant it. You told me you understood that-"
"I didn't say I knew you'd leave me," Itachi whispered softly. "I said I knew what you'd do."
Kisame crossed his arms and frowned at his partner. "You're not serious, are you?"
"…"
"How the hell did you supposedly 'know' that I'd stick around to help you if you got injured, huh?! Especially when I told you the complete opposite!"
Itachi gave his partner a look that was somewhere between patience and pity. "I just did."
"How?!"
The Uchiha shook his head and pulled his comforter up over his head. "Figure it out yourself."
Kisame clenched and unclenched his fists, swore, and then stormed out of the room, slamming the door shut behind him. He needed to step outside the base for a bit, and preferably destroy some targets with his sword while he was out. "What the hell is with that kid?!"