This probably isn't going to make sense to a lot of people, except me. I will clarify if needed, just ask.
Spoiler alert. Well, in the manga, Itachi and Sasuke are fighting – the battle is still in progress, so the result is undetermined. People are debating or not whether Itachi will live or die.
-Freedom Tastes Like Insanity-
There was no way he would die there, bloodied, drowning in the red that no longer colored his eyes. Injured, limping, struggling, for the first time, with a smile, Itachi dragged his battered limbs across the chipped stones. He stood, there was no way he was going to die, and staggered along the blurry path forward, a trail of crimson threateningly following him.
Itachi refused to fall again, laboring, and overwhelmed by pain, this time, he was the survivor – he was free. His body, massacred, faltered, but his wheezed breaths, through aching lungs and clenched teeth, seething, hissing, kept him going. Although his own energy flickered as a light bulb would, burning the last filaments, he need only stumble a little farther; he would not succumb to the darkness, not yet, not now, not so soon.
Kisame was waiting, unsurprised by the destruction of his ally. He expected it, just as his partner anticipated it. As Itachi lifted his face, smiling up at the mist-nin, Kisame shook his head and wiped the blood from Itachi's chin.
''Satisfied, Itachi-san?'' He murmured, a sigh weighing upon the impact of his words.
The blow, sarcasm and concern, seeped in through his wounds.
''I am…'' He let his façade fall, even though he remained standing.
He allowed Kisame to pick him up and run throughout the trees. There was not much blood left in him, enough to keep his heart beating and aching, as it always did. He could spare it and endure – an Uchiha, resilient and strong, although the younger saw his tricks, he was not yet ready to win the battle. There would be a next time.
This time had passed.
They fled and bled and vowed to return.
''Can I kill you?''
Kisame smirked and looking down at the red staining his clothes and his partner's eyes, he nodded.
''You already have.''
Itachi was still smiling; it felt nice.
There was no one to break his smile. Kisame would not; he treasured the rarity, touched it with his fingertips, and kissed it, as they escaped, together.
The taste of pain was delicious. It faded though and the bitter adrenaline of numbing endorphins was all that was left. He could not savor it but he still craved it. Victory tasted similar, sweeter though, a saccharine that melted the taste buds. There was nothing in his mouth but a metallic tang; he sucked on it, the blood, and enjoyed the acrid of the moment.
Nothing was coherent anymore – his senses, spurned, abandoned his body. There was only a steady thud, a rhythmic beat, and a serene smile left. Kisame stopped and began to heal the wounds, as Itachi lay unflinching, but still there, grounded in the real.
''I'm glad you enjoyed yourself…'' He said, eyes fixed on the delicate curve, bleeding with malice and anger.
Itachi was insane, smiling at a time like this, senseless and carefree. Kisame did not understand; he accepted Itachi's embrace and kissed his partner, just like he wanted him to.
Yea, that didn't make any sense. I'm sick (physically, this time) and killing time.
I guess the only explanation I can offer is that, like the last paragraph states, Itachi is insane, but only after the fight with Sasuke does he accept it, if only momentarily. (yes, he will survive people, get over it) He'll most likely go back to being stoic and composed Itachi, but for that one moment, he's free…to be something else.