Kisame maybe OOC... too bad. I think he would be the most accepting of some random kid than the rest of them.
As for the constant changing of tenses, Itachi is telling it in the future, but the important parts are written as though its happening now. Let's say he remembers those bits the most.
When I awoke, once again the familiar weight was on my chest. I cracked my stiff eye lids open to see Sasuke staring intently at my face. There was no way of telling how much time had passed since the brief struggle. We were inside a traditional styled Japanese house, but all of the screens and shutters were closed, creating dimness.
"Niisan!" he said, obviously relieved.
"I did say he'd be alright." a male voice replied in a somewhat impatient tone.
My whole body was still stiff from the recent dose of poison, so I had difficulties when turning my head to face the unknown speaker. I found he was a... large blue man, whose resemblance to a shark was uncanny. He had shark shaped eyes, dorsal fin-like hair and even gills.
He grinned as he noticed the small signs of surprise I allowed to show. He even had pointy teeth. This man too was wearing a black and red coat. It must be the Akatsuki uniform.
Still, as friendly as this man appeared to be, I couldn't take chances. I held Sasuke protectively, activating my Sharingan. The grin vanished as he instantly became serious, picking up a large sword which had previously been leaning against the wall behind him.
"It's ok Niisan." Sasuke said, poking my arm to get my attention, "He looks different, but he's ok, not like those other two..."
He was right, this man wasn't like the other two. For a start, hadn't yet tried to attack me yet. That was a pleasant change.
I lifted Sasuke off of me and managed to get all the way from the futon to my feet without too much difficulty. Bowing as low as my stiff muscles would allow, I said, "Uchiha Itachi." and then managed to stand again.
"Hoshigaki Kisame." he replied, nodding his head and lowering his sword. There was some awkward tension as Kisame didn't lower his sword and I didn't deactivate the Sharingan.
Oblivious to this, Sasuke asked, "What kind of sword is that Kisame sama? Why is it wrapped up?"
Kisame obligingly unwrapped half of his sword, exposing a purple spiky... thing.
This instantly broke the tension. Small things, small things...
"You haven't heard of the Samehada?" Kisame questioned.
"Same...hada?" Sasuke asked curiously, walking closer to get a better look. I allowed this, knowing Kisame wouldn't do anything to hurt him... at the moment anyway.
"But every child in Kirigakure knows the legend of the Samehada! The sword that shaves people to death and can eat chakra!"
"Can it really eat chakra?" Sasuke asked, a little skeptically. Skeptical at seven, maybe we were more alike than I thought.
'Most likely otherwise he wouldn't be here.' I thought, but let Kisame continue his story. He probably found my brother easier to talk to than myself, understandably.
'Correct.' Leader thought at me, 'You're quite observant I see.'
'Is there any particular reason Kisame san is being so friendly towards my brother?' I wondered, paranoia getting the best of me.
'Well, you being more powerful than him, I suppose he needs to have some kind of safe guard. Besides that, I have decided that he will be your, ah... 'partner in crime'.'
'What of Sasuke?'
'Your brother can stay here. He is safe under my protection.' Leader replied.
'...you seem quite keen to take me in. It's almost too convenient.'
'Let's just say the Mangekyou Sharingan is almost essential to our operation. If anything should happen to you, we still have your brother as reserve.' It was almost a threat, but before I could respond, I felt the mental connection break.
"Niisan! Come look at this!" Sasuke called, awestruck.
"Hm?" I asked, coming up behind him, resting my hands on his shoulders. He looked up at me, I couldn't help but think, exposing his throat. "Isn't this sword amazing?"
I smiled briefly, "I wonder if its weilder is as prestigious?"
Kisame had a look of mock indignance, "Of course Itachi sama."
I wasn't expecting 'sama'. Leader was right, Kisame knew I could kill him and he was obviously trying to get into my 'good books'.
"Sama is odd. Please, san is fine. We're equal." I had to protect my brother. I had to be in his 'good books' too. Better to have a friendship than a relation based on fear.
Kisame seemed a little miffed by this response, but just nodded in acceptance, "Itachi san." he corrected.
"Niisan, do you have any food left?" Sasuke asked.
"No, they've taken everything including my weapons." I replied, patting him on the head apologetically.
"Well, it's about time the evening meal is usually prepared." Kisame said, "Konan sama may have prepared something by now."
Sasuke looked up hopefully. He was hungry? He'd eaten three quarters of the food. He must be growing... Kisame indicated the kitchen was just up the hall way.
Sasuke grabbed my arm, not wanting to leave his comfort zone yet.
Well, that's about it. Hope it didn't get too sloppy towards the end. I'll fix it later if it did. Excuse any typos, I'm half asleep again!