AN: A series of interconnected one-shots. Originally posted to tumblr for their October 2015 KakaSaku Month prompt, "Soulmates". Huge kudos and thanks to everyone on tumblr who encouraged me to keep it going into a full story, and especially to AijoInu and sleetfallrain for their immeasurable help and beta skills. All errors remain my own. Loosely inspired by YoukaiYume's age-swap AU, and several others. On with the story!

(In the beginning - age 6 - Genin)

Frowning beneath his face mask, Kakashi stared up at his sensei.

"Sakura-sensei?"

"Hmm?" She smiled down at the lad from behind the scarf that forever covered the lower half of her face.

Something twigged at his memory, elusive as mist, leaving only faint traces of feeling and emotion behind before they, too, dissipated.

"Kakashi-kun? What is it? I recognize your thinking face," she said, poking him gently in the cheek. Her roseate hair slid forward over her shoulder and Kakashi's strong, little fingers itched to touch it.

Do you ever feel like things are backwards, and I'm the one supposed to be looking after you?

Not that he'd ever say that to his sensei; he would never suffer her that's-so-cute!-expression… not for that.

"Nothing."

She watched him from the corner of her eye as they continued walking through the village.

Her idiot former teammate, Naruto, waved madly at them as they passed him and his genin team at the training grounds. Kakashi was sorely tempted to leave a trap or two near its entrance, but sighed to himself when he saw the blond's best-friend eyeing him. Hmph. Damn Uchiha was too attentive. He postponed the plan until the walk back.

"Is your team AWOL?" laughed Sakura as they passed Sasuke, her other former teammate. The Uchiha was leaning against the entrance to Naruto's team's training ground, with apparently nothing better to do.

He huffed through his nose. "Collecting their packs to meet at the gate. Mission."

Beneath his own mask, Kakashi's cheeks burned with jealousy. He had no team, which limited him greatly. No one wanted to put up with a 'kid', especially if that kid was better than they were. His last three teams had rejected him; Sakura was his third sensei, and so far, the longest-lasting one. No other teammates had been assigned to him.

He hoped to keep it that way.

Which meant getting through the too-knowing Uchiha blocking their path.

Sakura frowned at Sasuke, raising Kakashi's hopes.

"You're leaving now?"

The Uchiha's expression softened. "I'll try and be back in time."

"You better."

They held each other's gazes for a beat. Then another.

Kakashi's brow furrowed in consternation. Ugh.

Perhaps he should move things along himself.

He tugged on Sakura's sleeve. "Sensei, katana practice? You promised."

She nodded, smiling apologetically to Sasuke. "Catch me when you come back."

He nodded, then looked down at Kakashi; a glint in his dark, knowing eyes. "Things going smoother since you got a private sensei, hn?"

As if he was lowering himself to the Uchiha's level. Kakashi gave him an unfriendly, half-lidded stare.

He heard Sakura coughing behind her hand. "Good luck on your mission, Sasuke. Leave my student alone; he'd give you a run for your money."

"Hn."

Sakura shook her head at him, giving him a quick one-armed hug which, to the Uchiha's credit (or discredit), he leaned into and returned right back.

At least until his expression flinched. "Tight," he grunted.

Sakura laughed and released him before sauntering away, Kakashi at her side. "Wuss."

"How many ribs did you crack?" Kakashi asked as they passed another training field. He looked up at her to see her scratch her cheek, just above her scarf. The breeze blew wisps of her petal-coloured hair around her lovely face.

She smirked at him. "Just one or two. This time." She bit her lip before throwing back her shoulders and looking at him proudly. "No one teases my student."

Then she reached down and ruffled his untamed mane of silver hair.

He turned his patented baleful stare on her. "Sensei…"

She laughed at him, and nodded her chin ahead of them, a glint in her emerald eyes. "Training ground seven. On your mark… get set… go!"

He was off like a shot, leaving a trail of camouflaged caltrops behind him.

"Ow! Hahahah! Nicely done, but I'll get you for that!" She laughed, giving chase.

Behind his mask, Kakashi let himself grin.

Just the two of them.

The way it was supposed to be.

Sakura glanced over at Kakashi and her eyes creased as she smiled at him from behind her raised collar. His eyes dropped to where her mouth would be, then back up to her eyes again.

"Sensei?"

"Hm?"

"How come you always keep your mouth covered?"

"Ah, I have terrible teeth!" she said with a laugh. With an exaggerated gesture she covered her mouth and widened her eyes comically.

She reached over to ruffle his hair and he pursed his lips behind his own mask.

Their travel to Suna as messengers was quiet and relaxed as they crossed through the deep forest. As the mission was a 'B' rank due to the travel, normally a Genin team was unable to accept it. Luckily for them, Sakura-sensei was ANBU-ranked, and though he was only a Genin, Kakashi knew she'd wiggled it out of her Shishou, the Hokage, to give him some time to conduct proper missions.

"You're strange," he said, voice flat.

"Sure am," she said, still smiling.

Strange enough to find the type of mission he could not only do, but do well, and mostly autonomously. She'd let him take the lead through most of the mission.

He looked around. This section of the wood had towering trees with large whorls to land upon…

He looked up, then looked over to Sakura-sensei.

She grinned at him, and winked. "Go for it."

Anticipation rushed through him as he leapt into the trees… and against his training he let out a quick, "Whoop!" as he raced along branch after branch.

He felt Sakura chasing after him, calling encouragement and remonstrations, as she felt necessary.

He felt alive.

There!

It was late afternoon on their mission and Kakashi flipped off the massive tree trunk and it exploded a split-second later. He spun in the air and had planned his next six moves before his small body was bulldozed to the side, careening across the forest to crash, bumping and rolling, far down on the forest floor below. His vision swam.

He made out a blurry shadow to his left. "This? This is what Konoha thinks of us? They send their freaking kids out to escort classified intel?"

The nearest voice echoed behind Kakashi's fuzzy eyes as he strained to get his bearings. Where had he landed? Where was—

There came a gurgling noise again from his left, then a soft, heavy thunk as a pair of bodies hit the ground together.

Another two fell a second later, and finally the last. There had been six, he remembered then, and he'd taken out one while Sakura dragged their attention away from him. She had drawn them almost all away, yet they had still gone after him when they realized who she was.

Pushing himself up, he stumbled to his sensei, grabbing hold of her red tunic. "Sensei, are you okay?"

"Kakashi? Oh, thank kami." She dropped to her knees beside him, her hands already glowing. "Let me take a look at you. Your eyes are unfocused, did you hit your head? Come here, baby."

He scowled at her. "I'm a shinobi, I'm not a—" His eyes shot open as he felt the shadow falling across them before he saw it.

Then he was being thrown to the ground again and rolled to the side, covered by a firm, muscled body that was three times his size.

Sakura's arms wrapping tightly around him, she shuddered twice, three times, four… his breathing was rapid and ragged when he suddenly felt Sakura-sensei tear herself off him and fly back at their missed opponent, her scream of rage and sheer power sending shivers up and down his spine.

Her glowing fist tore right through the enemy, and she ripped her fist back before kicking him out of her way, then opening up a crater in the earth to fall into.

Before his young eyes she palmed the earth and shot chakra out, ensuring there were no enemies left.

It was then he saw her back, peppered with kunai and senbon; her tunic becoming more and more crimson.

She glanced back at Kakashi, then, her fierce gaze softening. "Come here, baby, let's get you healed."

Kakashi nodded. His arms were still trembling as he sat obediently in front of her. He didn't miss the hand-signs she cast before she began healing him.

"What was that for?"

"Hm? Just calling some friends." She smiled at him, falling to her knees. "Now, turn your back to me so I can take a look at it."

She healed him before they set back to walking again, though Sakura adjusted their route. "We're going to check in with someone first before we get back on our way."

His eyes flicked up at her back and she turned to face him. "Hm?"

He swallowed.

"It's okay, we're fine. We'll be there soon. Promise!" She smiled down at him, sweat beading on her brow beneath her hitai-ate.

Two hours later, she called a short break, and re-formed the hand signs from before.

Kakashi watched her, and memorized them.

They set out again, though their progress was much slower. Sakura-sensei was leaning on the trees occasionally.

Darkness fell, still they walked, though it could barely be considered progress.

"Should we camp here, Sensei?" he asked, sticking close to Sakura's side

Sakura swallowed, her voice hoarse, her breathing hollow. "Not yet, we're almost there."

Kakashi eyed her dubiously.

She closed her eyes and rested her head against her arm, which pressed against the tree. "Almost there.

"Keep going," she said, forcing her voice to sound positive.

Kakashi nodded, and mentally practiced the hand-signs she'd been doing.

When she fell to her knees, the moon was high in the sky above the canopy. When he reached out to catch her, Sakura gently pushed him away; her touch burned him like fire and she was soaked with sweat.

"Sakura-Sensei, I think you've been poisoned." Kakashi's mouth was dry.

She chuckled, her head falling forward when she tried to nod. She put out her arm to brace herself when she fell forward. Settling on her knees, Sakura brought her shaking hands together and tried to form the seals one last time. Her coordination failed and she sighed.

"Kakashi?"

"Hai, Sensei."

She let out a hoarse exhale. "I need you to do something for me. I need you to keep heading north, and don't stop until you meet the ANBU. The Konoha ANBU. You know what they look like, right?"

Kakashi nodded. "Hai."

"Good. You… you do that. I'm going to take a quick break before I follow."

Shaking his head, his fingers trembling, Kakashi reached out to touch Sakura. "But… We're supposed to stick together."

"Hah, yeah," she panted, before slumping forward. "Sometimes you need to keep going, though. You start moving, okay? I'll be right behind you."

"Hai, Sensei," he said, confident.

She nodded, her eyes remaining closed, before she fell to the ground in front of him. She turned away from him, so her movements were shadowed, and pulled down her scarf; she took a deep breath and touched a glowing hand to her throat. It was too dark for him to get a look at her face before she collapsed entirely, her face covered once more.

His heart thumped hard, before his adrenaline kicked in.

And then Kakashi took off his pack, and dragged a branch closer to sit upon to get a better vantage point, and he took up guarding his incapacitated sensei.

And he began practising the hand-signs she'd been forming, over and over again.

It was all he could do.

Ten kilometres away, the ANBU sentries looked at each other inside their station.

'And Konoha confirms they sent no new ANBU teams this way? That is definitely an ANBU call-sign."

"None, sir. The call-tag is several months old and was replaced weeks ago. It was approaching our location for hours, but has remained stationary for the last forty minutes."

"Had Konoha sent any teams this way?"

Another subordinate shook her head. "No sir; outside of one message delivery mission, there were no teams scheduled for passage through our territory."

"Who was on the message delivery?" The ANBU commander asked, curious. "That shouldn't have required an ANBU, or it would have gone through Central."

But then he felt the burning and forced himself not to react, even as his subordinate replied, "Haruno, Sakura, sir. And she has a Genin with her." The subordinate's eyes widened. "It's Sakumo's son, sir."

"Medical escort, immediately, to the last known location of that beacon-call," ordered the ANBU commander. He strapped on his tanto and leapt to the window. "Be prepared for medical evac."

"The beacon is still coming in strong, sir."

"But it's not moving," said the other, more quietly. "And if it's Sakura, and she's with a child, why couldn't she pick him up and just keep going?"

Fingers sore, raw and bleeding, Kakashi scrambled for his kunai as he stood over his Sensei. Someone was out there. He had covered Sakura-Sensei up as best he could with her blanket, and his, but he hadn't dared light a fire. It would draw enemy nin to them in a heartbeat.

"Peace, Hatake," came the smooth, low voice from in front of him.

Peering through the night and shadows, Kakashi tightened his grip. "Who's there?"

"ANBU-san," said the commander, stepping closer. He lit a fireball and hung it in the air. "Are you alright?"

"Yes. But Sakura-Sensei's not moving. And she's not really breathing well. A-and she's bleeding." He swallowed, and tightened his jaw. He was a shinobi. He had to be strong. He had to protect Sakura-Sensei. "Poison."

The ANBU nodded. "Let's get you both back to the base and take a look. Follow me." He moved to pick up Sakura-Sensei, when Kakashi leapt in front of him, kunai raised.

"Don't touch her. Who are you?"

The ANBU looked at him, his eyes pinwheeling. "Now is not the time."

Kakashi glared at him right back and swiped the kunai up, fast, faster than the ANBU had even been expecting. It slit the straps that held it to the ANBU's face, and the ANBU let it fall.

There, before him, stood the terror of the Konoha ANBU ranks. The coldest, most ruthless killer Konoha had ever known.

"Collect your things and follow me," said Uchiha Itachi. He picked up his mask and slid it into his vest. Then he gathered Sakura in his arms.

"How did you know where to find us? I've been calling for hours."

Itachi sped up, until Kakashi was racing alongside him, then further and further behind him as Itachi poured on more speed. "We have ways of locating our own," he said.

Kakashi pumped his small legs harder, faster, stronger, but still the Uchiha outstripped him. "Where are you taking her?"

"Taichou! There you are! We were searching for—is that—"

Kakashi heard another voice and saw another masked ANBU join them from the side, another two behind them.

"Take care of the child; I'll take her back to base. Hurry."

With that, Uchiha Itachi disappeared from sight.

The three remaining ANBU turned their masked faces towards Kakashi.

He swallowed and held up a hand. "Yo."

They looked at each other, before one shrugged and looked back at him. "You're coming with us, kid."

"I'm not a kid. I'm a shinobi."

"Come on, let's go check on your Sensei."

(Several months later)

Nothing about the dark-haired man shifted or indicated he'd even sensed Kakashi nearby; but he knew better. Sasuke entered the traditionally structured building and disappeared from sight.

Frowning under his mask, Kakashi scanned the onsen's doorway; there way no way he could follow Sasuke in there, it would be too obvious.

That Uchiha always knew when he was around.

Pulling back from the pointed rooftop ledge he'd been observing from, he took a breath and re-evaluated his strategy.

(An hour later)

"You jerk!"

From his spot up on the rooftop, Kakashi peeked over the ledge.

The angry shouting reached his ears easily, but no one had come outside. Yet.

"What do you want, dead-last?"

"You! You dared make a date with Sakura! Without me!"

"Hn. Jealous?"

"You admit it!"

A heavy, exasperated Uchiha-sigh.

"You're being an ass. It's not like that."

"The Hell it isn't! You promised, bros before hos—you're breaking the covenant of the bro code!"

Sasuke gave another sigh when Kakashi heard rustling.

"What are you doing now?" asked the Uchiha.

"You can't break the bro code. I won't let you."

There was an ugly pause.

Then, Sasuke's voice turned dark, suspicious. "What did you do?" More rustling, shuffling noises. "Where are my clothes, Naruto?"

"I did this for your own good. You two-timing, backstabbing bastard."

"Where are my clothes?"

"There are consequences to every—"

"What did you do with them!?"

"You forced my hand!"

There was a yellow-blond flash that dashed out of the onsen's curtained doors, and a malevolent black storm that screeched to a halt just shy of them. The curtains cast shadows over ten pale, very naked male toes that curled against the hardwood.

With a small, happy sigh, Kakashi smiled behind his mask before sneaking back up the roof again.

Perhaps Sakura-sensei would be able to join him for ice cream that night, after all.

AN: No update schedule set for this one yet; I'm writing the last chapter and finishing up the edits, though. Please let me know what you think!