This is set during the Zanpakuto Unknown Tales arc (I...think), a little "behind-the-scenes" leading up to when Kenpachi arrives at the battle scene. Basically, what inspired this is their exchange wherein Yachiru complains about them running straight past a candy store, and Kenpachi telling her that he promised to take her back there.

Pinkie Swear

Trees collapsed on either side of them as Kenpachi tore through the forest, sprinting at breakneck speed to get to the Seireitei. Just when he had thought that there weren't anything better to do than cutting up hollows, news reached him about some "zanpakuto rampage" in the court. Apparently, zanpakuto spirits were running amok, turning against their owners and causing a riot.

The moment Kenpachi heard it, he sliced up the last of the hollows, urged Yachiru onto his back, ignoring her itchy hands that automatically started victimizing his spikes, and made a beeline for the Seireitei.

That had been more than two hours ago, and still he hadn't caught sight of the court walls.

"Oi, brat! Ye sure 'tis the right way?" He turned his head slightly to look back at Yachiru.

"Yep, I'm sure of it!" She flashed him a wide, confident grin.

"Ye sure? Like, really sure?"

"Don't 'cha believe me, Ken-chan?" She knocked him on the head, causing him to focus on the road before them and dodge an overhead branch at the very last minute. "Pay attention, Ken-chan, or we'll get even more lost!"

"'More lost'?" This time he spun his head as much as he could to stare at her through his one eye. "'More lost'? What the hell's that supposed t'mean?"

"It means," Yachiru grabbed little fistfuls of his hair and pulled hard, "you weren't payin' attention to my directions!" She slapped his forehead. "Bad Ken-chan!"

"But ye gave me the wrong directions, ye brat!"

"Did not!"

"Did to! Now we're goin' in fuckin' circles 'cause-"

"'Cause Ken-chan's stuuuupid."

Kenpachi gritted his teeth and let out a nasal breath, commanding himself to stay calm. Cutting up the brat right then and there didn't sound like a very pleasant idea…and without her "directions", he'd most probably end up even more lost.

"Suit yerself, runt," he spat, winding his way through the trees. He had known from age-old experience that there was no arguing with Yachiru. Whatever she said, she'd want everyone to agree with. It was bad enough having his spikes messed around with – he didn't want to end up like Ikkaku and have his head bitten into.

"KEN-CHAN!"

At the sound of her ear-splitting scream and the hard tug on his hair that nearly tore a spike right out of his scalp, Kenpachi skidded to a stop. Yachiru had grabbed his head with both her hands, and by now was shaking them like one shook a stubborn bottle of salt.

"Crazy-ass runt." He swiped her hands away. "What the hell d'ye want now?"

And then he saw it. The damnation that sat just feet away from him, complete with stuffed toys and colourful, spinning paper windmills, and when he turned to Yachiru, she had fixated that look on him that made him want to go to an old woman and beg for a child-raising manual.

"No, runt. Not now," he managed to say, but only through gritted teeth, and it came out half-hearted and meek.

"But, Ken-chaaan!" Her lower lip started trembling, her clutches on his shoulder tightening. "I want caaandy!"

"Ye can't have them now, Yachiru. C'mon, I got a big fight comin' up, an' if we go in…there, we'll miss out all the fun."

She stared at him with wide, unblinking eyes. "Please?"

He stared back at her, the sides of his mouth twitching. "No can do, brat."

As expected, tears started welling up in her eyes. This had happened countless of times before, and Kenpachi knew exactly what he should do, but still he couldn't help but feel a dull ache deep inside his chest at the sight of her sniffling.

"Listen, I'll take ye back here when we've settled all that bullshit in the Seireitei, all right?" He reached out and ruffled her hair, grinning in reassurance. "Don't worry, the candy'll still be here when we get back, and if it's gone we'll jus' go look for another better place. Simple as that, eh?"

She sniffed and swallowed. "Ye sure?"

"When am I not sure, eh?"

"When you were goin' through the forest and lookin' for the Seireitei and you didn't know where you were goin'."

Kenpachi made a face, and Yachiru giggled at his disbelieving expression.

"Ye don't believe me, do ye?"

"I'll only believe you if," and here she held out a hand with her little finger extended, "you pinkie swear."

Kenpachi stared at the finger, then at her. She pouted and waved it in his face. When he continued to stare, lost for words, she let out a sob. With a sigh, he gave in and hooked their little fingers together, making sure that he didn't squeeze too hard so that he won't break hers.

"It's not enough if you just do it, Ken-chan..."

"All right, I pinkie swear that I'll take ye back here to buy the whole goddamned store!"

"Really?"

Kenpachi froze and swallowed, realizing what he had just said, but when Yachiru started squealing in his ears and tugging at his hair, he was only capable of a sigh.

Really, whatever Yachiru wanted, she got it.

He raised his hand, little finger extended, and let out a scoff. Pinkie swear or not, he'd most definitely bring Yachiru back here.

That bright, ice cream-smudged smile on her face was what he fought for anyway.

A review would be nice. :)