Disclaimer: I don't own Naruto. I'm just playing in Kishimoto's sandbox.
Author's Note: This is pure speculation born of a chat with singeivoire (go read her fics!), though it would be awesome if it were true. Spoilers for some of the manga but nothing plotwise. Takes place in Shippuden, after they've met Yamato.
Sitting in his room, his well-thumbed copy of Make-out Paradise in hand, Kakashi glanced up at the clock by his bed. The hour hand clicked over to midnight. He closed his book, dog-earing the page he'd stopped at, and stood to pull on his green flak vest. Time to go.
His route across the roofs of Konoha was eerily quiet as he'd concentrated his chakra to cushion his footfalls. Hokage Mountain soon loomed above him, the huge faces sinister with the shadows of night. Kakashi descended from the rooftops into a long-abandoned section of the village—the Uchiha complex. In the old days when Sasuke still lived there, this trip had taken longer as he'd had to go out of his way to avoid the apartment where the last of the Uchiha clan slept. It wouldn't do at all for anyone to see him—not then and not now.
Kakashi paused at the front of the crumbling façade of the Military Police building, glancing down the dusty street, even lifting his forehead protector to let the sharingan examine the area. Nothing. Not even a cat in the alley. Lifting his hands to form a secret seal that the Third Hokage had shown him personally, Kakashi stepped through the genjutsu and entered a dark room.
He felt the kunai at his throat before he saw the porcelain mask of the ANBU guard loom out of the darkness. Kakashi kept still, knowing this would be over in a moment.
"Kai!" the ANBU guard lifted his hand in a seal, but his face was hidden by the mask so Kakashi couldn't tell if he was surprised when nothing happened or not. Another guard, stocky and silent, took the package Kakashi had tucked under one arm.
"They say," the ANBU said in a monotone, "that it was Shodai's wood element jutsu that created the village…"
"But it is a will of fire that sustains it," Kakashi finished. The ANBU nodded.
"Remove your vest," said the guard after a few more minutes of other hand seals, all designed to uncover any potential mischief.
Kakashi kept his movements slow and visible, knowing that this guard and the other hidden ones were under orders to kill at the slightest hint of trouble, even after the countersign. Kunai holster followed the vest along with his two hidden daggers. They allowed him to keep his forehead protector, after a brief examination, and the package he brought after even more examination—then he was allowed to continue through the room, past another guard, to the flight of stairs.
He walked for what seemed an eternity until the wood of the building had long faded into the dark behind him and the walls and steps were entirely cut out of stone. He reached the top, stopping as a dazzling light burst in front of his eye.
"Good evening, Kakashi-san. Sorry about the light."
"No problem," Kakashi said, squinting as the beam of light shuttered. It was designed to dazzle potential enemies into pausing as he had, giving the ANBU a few precious seconds of advantage. The ANBU agent waited until Kakashi's eye adjusted and then walked with him through the stone corridor.
"How are you, Taishi-san?"
"Very well, considering. How's your team? Has Naruto-kun made chuunin yet?"
Kakashi cast a glance at the ANBU operative. "You've met Naruto?"
"No, but I hear about him… often."
"Ah, yes, of course." Kakashi paused. "He's doing well. A new training technique we're trying has allowed him to progress much faster than usual, which is always exciting for him. I have every confidence that he'll make chuunin in the next exam. Technically, he's been chuunin level for quite some time. The test will be a mere formality to confirm it."
The ANBU nodded politely.
"So how has he been since my last visit?" Kakashi said, switching tacks. He glanced at his companion, though the porcelain bird mask gave no indication of the man's expression.
"The usual, sir. He has his good days and bad days—" Taishi broke off as a torch illuminated a burnt patch on the wall. The rock was charred and black, pockmarked, and grotesquely bulging in places where it had melted and started to drip down the wall before cooling into place. "That was a bad day."
"You let him out?" Kakashi was incredulous, and he gripped the paper-wrapped bowl in his hand with white-knuckled fingers.
The ANBU's shoulders hunched slightly, the only sign of embarrassment Kakashi could see. "This is a rough job, Kakashi-san," he said in a quiet voice. "One minute he's pleasant and witty—like a favorite uncle and you can't believe that someone like him is locked away in a place like this. They wanted to let him stretch his legs. But then—" His hand waved at the molten patch of rock.
"Ah. So that's why there are two more guards up here."
The ANBU stiffened; then laughed wryly. "No sense in denying it to Sharingan Kakashi. But they would prefer it if you at least pretended not to know they were here."
"Point taken."
They continued walking in silence for a few more yards until stopping at an iron-shod door with no visible doorknob or even a keyhole. Only a paper tag marked with the kanji "seal" covered the crack between the door and the wall.
"I leave you here, sir. Yell if you need help or if he starts… Well, you know." The young ANBU guard's voice held just a touch of fear, not that Kakashi blamed him. Even he couldn't forget what exactly the man behind the door was. He nodded, turned to the door, and formed the second secret seal that no one in the village besides the guard he just left and Godaime herself knew.
The iron door hissed open as the seal released, and Kakashi stepped through.
In the darkness of the cell, he lifted his forehead protector and felt the chakra leech as the sharingan whirred into focus. Immediately he could see the simmering ball of red chakra in the darkest corner of the cell—though safely behind an iron portcullis of course. A rumbling growl sounded through the cavernous stone room, and he could see two glowing red eyes staring at him.
"Ka… Kakashi-kun?" The voice alternated between a light tenor and a rumbling, beastly growl. The red eyes blinked slowly. Kakashi stepped forward and slid the bowl he'd brought under the low hole in the iron-barred wall.
"I brought you a present," he said, stepping away from the bars. "I'm afraid it's not as warm as it once was, but they don't exactly have microwaves up here, do they?"
The eyes moved to the bowl. Kakashi heard the sound of paper tearing and then, to his relief, a joyful, human laugh. "Ramen! How did you sneak it in here? By the way, turn the light on, will you?"
"I'm sorry I couldn't bring any chopsticks. The guards confiscated those. Something about pointy objects," Kakashi said, patting along the side of the wall until finding the light switch, an incongruous plastic against the stone wall.
The other man snorted. "Funny thing is, I'm not a danger to myself unless It gets too out of control. But with the chakra repression drugs they have me on, that hasn't happened in years. It knows better than to make me hurt myself, because if I die, It does too." Slurping sounds came from the cell.
Kakashi turned back to the cell and sat down on the floor, regarding the other man as he ate. Dirty blond hair, matted and long, framed the man's thin face. At one point he had been handsome—the crooked nose had been once been unbroken, the blue eyes didn't always have a tint of red, and the deep, dark marks on his cheeks that looked like whiskers had not always been there either.
"Ah," said the man, licking his lips to catch any stray drops of ramen broth. "That tasted like heaven." He swiped the sleeve of his shirt across his mouth and looked at Kakashi, his eyes suddenly serious. "How is Naruto?"
"Good. I wish you'd thought of that technique about using shadow clones to learn new jutsu earlier. It would have saved Naruto—and me—a lot of trouble."
The other man grinned at Kakashi's tone and tapped the side of his head in a knowing manner. "Genius, remember?"
"As if you'd let me forget," Kakashi said in a dry voice. "I believe that's how you introduced yourself to me… sensei."
The former Fourth Hokage chuckled, eyes crinkling at the corners. "No, no. You're mixing things up. That's how you were introduced to me. I'll never forget the proud way your little finger jabbed itself at my nose and then how you informed me with all the seriousness a six-year-old can muster that you were a genius and that you didn't need a jounin sensei."
Kakashi rubbed the back of his neck with an embarrassed laugh, and the two men, master and student, sat in silence for one peaceful moment. But, of course, it wasn't to last.
"You know, Kakashi, I'm sure if you brought Naruto with you someday, I could teach him all kinds of things that would make his training easier!" The words were spoken in a light, offhand manner, but Kakashi wasn't fooled.
"You know why we can't do that," he said in a gentle voice. "It is bad enough that the yang half of the Kyuubi's chakra resides in Naruto, and that the yin resides in you. You know that the yin is the stronger—that's why you took it upon yourself—and your seal is weakening, just like Naruto's. If the two were ever to come together…" Kakashi shook his head. "It is a risk we dare not take."
"Yeah, I know," came the words after a moment. "If only I had died like I was supposed to…" Minato gave a grim laugh. "Who would have thought that even the Death God wanted nothing to do with the Kyuubi? Perhaps the red chakra gives him indigestion."
Kakashi didn't reply. What reply was there?
"I take it the Tenzou kid is useful then?"
"Extremely," Kakashi said in some relief at the change of topic. "It's due to his abilities that Naruto's been able to progress so far in such a short period of time. He saved Naruto's life on their last mission." Kakashi paused. "I'm only sorry that it had to come at a cost to you."
The shadowy figure shrugged. "He's my son. I'd give my life to see him succeed, to see him live a normal life. I tried once and it didn't work, guess I thought I'd do it again." The blond's mouth twisted in a familiar grin that crinkled his eyes, hiding the dark circles beneath them. "Besides, now that they're giving me more drugs to replace the control Tenzou had over It, I'm a lot happier."
"Sensei—"
"No, really. They do something to my memory, so a lot of times I can't remember when I have a 'bad' day, so really, it's like It's not there."
He was lying and they both knew it.
"What was your name again?"
Kakashi's head jerked up, but the blond was grinning.
"Gotcha!" he chuckled. "Ha! You should see your face. But wait, you can't with that mask in the way!"
"Heh," Kakashi smiled wanly beneath his mask. The drugs must be affecting his old teacher more than he let on.
"Here," Minato slid the bowl back underneath the iron bars and withdrew his hands quickly, but not so fast that Kakashi didn't see how hard they trembled; like an elderly man with palsy. Perhaps it was just as well that the ANBU took the chopsticks; didn't look like the former Yondaime could hold them anyway.
Silence descended upon the cell.
"Sensei—"
"Hang on," the older man grunted and Kakashi saw, with alarm, the red center of chakra flare. Kyuubi.
"Stay down, you bastard fox," growled Minato, his voice growing deep as the red chakra continued to spread through his body. Kakashi waited, tense, his sharingan automatically telling his brain where his body needed to be should Minato lose control and leap for the bars.
Minato was gripping the sides of his head, but then his hands relaxed, and he looked up at Kakashi—his eyes were crimson. A feral grin stretched his mouth unnaturally wide.
"So you know where my other half is, do you?" Minato stood, his movements jerky, and gripped the iron bars, staring at Kakashi with the intensity of a predator stalking his prey. "Bring him to me!" he roared, the sound filling the room.
"You know I can't do that," Kakashi remained calm, though all his instincts were screaming that he leave now. "Sensei, don't let him take over. You know me, you know I've looked after Naruto for you. I swear that I'll protect him with my life."
Minato shrieked and seemed to push himself away from the bars, collapsing at the back of the cell. Kakashi's sharingan saw the red chakra begin to disperse and inhaled a deep, steadying breath. That was a close one. But the drugs were doing their job.
"Ugh…" Minato's voice sounded as it should as he sat up, pushing back the filthy tangle of his hair. "Kakashi-kun? What are you doing here?"
"Just came for a visit, sensei."
"Oh." He paused, blue eyes vacantly hopeful. "Is Naruto with you?"
Kakashi slept in the next morning to make up for how late he had stayed with his former sensei. When he finally arrived at the training grounds, Naruto ranted for a few minutes and then demanded to know what his excuse was this time.
Kakashi smiled behind his mask. "Sorry, Naruto. I was… chatting with an old friend and lost track of time."
"Liar!"
Kakashi looked up toward Hokage Mountain. "Yeah," he muttered, "that's exactly what I am."