Naruto was only really alive when he was with people, and especially with his friends. He thrived off attention, breathed conversation and laughter and bright smiles. He went to the greatest lengths to never be alone like he once had been, because when he was alone the world seemed so large and empty, with him rattling around in it, serving no purpose. His friends filled up the cold emptiness with warmth and happiness, and he returned that joy a thousandfold.
Sasuke was only really alive when he was on his computer, on the Internet. He revelled in anonymity, in illegal downloads just because he could, in online gaming, in hacking, in conversation on forums that the rest of the world would view as depraved or perverted or fundamentally wrong. When he left the comforting glow of his many monitors, he retreated into himself, he was silent and showed the barest of emotions.
Naruto's mind moved too fast for him to properly comprehend things as mere thoughts. It doubled-back and skipped over things and got distracted too easily. He needed to say them to understand them, to group the ideas into something understandable. He talked quickly too, he rambled and ranted and changed topics, but he always seemed to connect everything back to the original idea in a way that was impossible in writing or thought.
Sasuke was incapable of expressing his thoughts out loud. He had to write them out to communicate them perfectly. When he spoke, he found himself frequently wishing for a backspace, a CTRL+Z, a delete, and, more than anything, an exit button. If he didn't want to continue a conversation online, he closed the window. Real life was so much more difficult.
Naruto didn't like reading or writing or watching. He did and he was. He experienced the world first hand and saved it in glorious memories and impressions of feelings and verbal stories that changed a little every time he told them to someone new. These perfect experiences and imperfect recollections were the only way he could imagine living.
Sasuke didn't see why everyone whose jaws dropped at the number of hours he was on the computer per day told him that he needed to "get a life" or "enjoy real life". The pixels were the most real things in the world, in his opinion. Online, no one had to hold back. You could hunt orcs, assassinate kings, fight in World War Z, within the span of minutes.
Naruto liked chaos. The world wasn't neatly arranged, wasn't packaged into tidy little categories and ordered by subject. The world was disorderly, and wild, and it wasn't close to flawless, but those flaws made it beautiful.
Sasuke liked logic, and he liked the logic that computers were made of. If you knew the code, the numbers and letters and hyphens and brackets and parentheses all combined in the right way, you could do whatever you wanted. Your imagination could become your reality.
Naruto and Sasuke were opposites. They clashed and fought and conflicted and hated for an eternity of youth, but somehow that just drew them closer together. They could agree on almost nothing, they had completely different lives.
Somehow, they ended up as best friends.
[a/n] Should you not know anything Internet that Sasuke refers to, you can either Google it, PM me, or ask in a review. For the latter two, I'll answer to the best of my ability, in (hopefully) layman's terms. For the first, you'll probably get a better answer.