Disclaimer: I don't own Naruto, unfortunately.
Takes place right after Kakashi brings Naruto back from the Valley of the End.
"Kakashi-sensei, why does it hurt so much?"
Hatake Kakashi turned from the hospital room window to see a pair of blue eyes glazed with misery looking at him from the pillow. Naruto's face was almost hidden beneath all the bandages, but the older ninja didn't need his sharingan to see the pain knifing through the question. Kakashi considered his options. He could dodge the question by offering to get a doctor, pretending to think his pupil's question referred to one of his injuries, but that was a coward's way out. He owed Naruto more than that.
"It hurts because we care too much," he said after a moment, staring down at the bruised and swollen face. He remembered the surprising lance of agony that had pierced his heart when he arrived at the Valley of the End to see Naruto's little body stretched out and unresponsive; remembered the simultaneous fierce anger and immense sorrow when he realized what Sasuke had done. It had faded in the joy of seeing Naruto stir to life, but all the troublesome thoughts were coming back now that the immediate hurry was over.
Kakashi had come to care for his three genin more than he expected to. Perhaps that was the deeper reason behind why he'd never passed any genin in the first place. A sensei's relationship with his students was a close bond and with close bonds came the danger of those bonds being stretched to their limits, and even broken in some cases. Mother, Father, Obito, Minato-sensei, Rin, and dozens of other names carved onto the memorial stone… oh yes, he knew the pain better than he wanted to.
Kakashi was right to dismiss potential genin based on their failure of crucial issue of teamwork, even if some of the other village shinobi thought his methods too harsh. But there had been a number of talented genin with cheerful faces and ready laughter that would have been a pleasure to teach. He'd pushed them all back to the academy—their fragile dreams shattered or hardened into resolve to do better—and he, Kakashi, had been free to pursue his own way alone as a shinobi of the Hidden Leaf Village. But then these three had come along. Curiosity about the last of the Uchihas and the little boy that was better known as the container for the Nine-Tailed Fox had made him inquire to the Third Hokage about becoming their squad leader, but he hadn't expected the danger of what would happen if they passed his bell test.
"People like Orochimaru think they are strong because of their knowledge, by how many jutsus they have acquired; by how much power they think they have. They gather followers like Kabuto and Sasuke because of what they can do, not because they actually mean anything beyond their usefulness as tools." Kakashi looked out the window again. "Even Zabuza cared for that boy Haku in the deepest part of his heart, the part that he'd kept pushed down for so long. But Orochimaru is different. An appeal like you made to Zabuza on the bridge would not work with him. He feels nothing but the zest for his own ambition, cares for nothing but his own lust for power. Love is not something he knows or wants." He turned back to the little blond boy lying in the bed.
"We will hurt for a long time, Naruto. You, me, Sakura…but the pain is good in one way."
"How?" Naruto scrubbed at his eyes, but Kakashi saw that the bandages on his cheeks were growing wet anyway. "How can something that hurts this bad be good?"
"It reminds us that we are different than Orochimaru." He paused to let that sink in. "I have lost many good friends, many important people to me over these long years, but I would not want them back if it meant I would become as heartless and inhuman as Orochimaru." Kakashi hesitated, then reached out a hand to gently touch Naruto's messy blond hair. "The pain may never go away, but when we remember the friends we still have, it will get better, with time." The blue eyes looked up at him, still watery. Kakashi smiled, though Naruto couldn't see it through his mask. "We must never stop caring, right Naruto?"
"Right." Naruto rubbed at his eyes again, but his voice was stronger. Kakashi left a moment later; he was already late for his latest mission—Tsunade was keeping him busy despite, or perhaps because of, the whole Sasuke debacle. Hands in his pockets, Kakashi walked down the hallway from Naruto's room. Footsteps slapping against the tiled floor made him look up.
"Kakashi-san! I just heard!" gasped Iruka. "I couldn't get away—had to get someone to watch the students—how is he? And Sasuke?"
"Physically, Naruto's fine. Nothing a few days of rest won't heal, thanks to Kyuubi's regenerative abilities. I'm sure Naruto will be happy to see you." Kakashi paused. "Sasuke got away."
Iruka's eyes widened. "So… it's true then. He did go to Orochimaru. I didn't want to believe that one of my…" His jaw tightened.
"It's not much consolation, but Sasuke had to know that Naruto was alive when he left. He didn't finish it when he could have." Kakashi wasn't sure what to think about it himself, but Iruka needed to hear it. "It may mean nothing, perhaps simply that Sasuke was too beat up to continue, but I thought you should know."
The other man nodded. "Thank you, Kakashi-san." He turned to open Naruto's door, and Kakashi continued walking until he left the hospital. Like so many of his wandering walks, he ended up front of the memorial to the shinobi killed in action.
"You couldn't have done anything," said Jiraya, coming up to stand beside him. "Sasuke chose his path a long time ago."
Kakashi didn't respond right away. "He's not Orochimaru."
"And Naruto is not you." Kakashi turned his eye to the Toad Sage in time to see him grimace. "You're right, however," Kakashi continued, turning back to stare at the carved names on the memorial stone. "Naruto will need your training if he's going to survive his next battle."
"Gets under your skin, doesn't he?" the older man said after a moment.
Kakashi nodded. "Take care of him, Jiraya-sama."