Originally posted years ago on the ROTG KM, and found again recently after a few hours of combing through the prompts. I'm currently archiving a lot of my fics here and on AO3, but I fully expect to add a followup to this one sooner rather than later. Keep you posted!

—

I Trust You

Prologue

"Do not cross Jack Frost."

When he first heard this warning, Bunnymund was, understandably, a bit confused. It was early April, 1899, about two weeks after Easter. Two weeks after he met Jack Frost for the first time.

Bunny blinked at his companion. Punxsutawney Phil—The Groundhog—usually gave good advice, for all that he was a blighter. And he rubbed elbows with Winter Spirits on a frequent basis, as the ambassador between winter and spring. But he was also a know-it-all who took himself too seriously; a weasel faced rodent in a suit and top hat, and somebody had ta keep the little rat from getting too smug.

"He seemed like an alright bloke to me," Bunny said, hunkering back down in the earthy scents of his garden. And he meant it. Jack might have been annoying—their first meeting started with a snowball to the face—but comparing him to those other winter spirits like that was slander, at best.

Jack seemed good natured. Sociable. And non-cannibalistic, which, 3 for 3, was more than he could say about the entire Winter Court.

"Oh yes," Punx assured Bunny, polishing his monocle. "Jack Frost is undoubtedly the kindest Winter Spirit I've ever met."

"So then, why the ominous advice?"

"He seems to have taken a liking to you," the Groundhog explained, steepling his hands in a condescending way. "And you have a way of… how should I say this? …Vexing even the most easygoing of spirits. Why, it's a wonder you have any friends at all!"

Bunny scowled and went back to weeding his garden. He was starting to suspect that the Groundhog's unwelcome visit was less for Bunny's health and safety, and more a chance to gossip about him, and insult him to his face.

"Oh, when I heard that your paths had crossed, I rushed over here posthaste to ensure you were still alive and in one piece," Punx went on, ignoring Bunny's glare.

Bunny's nose scrunched up. "We talkin' about the same spirit here?" he asked finally.

Punx nodded vigorously. "I was certain I'd find your remains frozen and shattered, or smeared across your tunnel walls!"

Bunnymund rolled his eyes, head cocked to the side.

"Well, the Jack Frost I met couldn't scare the fluff off a dandelion," he countered.

The Groundhog leveled a firm look across the eggplant patch.

"Jack Frost," said Punx, "Killed Yuki-Hime, without even breaking a sweat."

Bunnymund choked. Yuki-Hime was a Japanese spirit, the Empress of the Yuki-Onna spirits who resided there, comparable in rank and power to even the Snow Queen. She'd died a decade ago, and rumors still circulated about who, exactly, killed her. There were few spirits in the world that held that kind of power.

"Frost?" Bunny asked at last, bewildered. "He looks like he couldn't snap a twig!"

"That's what many thought," Punx said, polishing his claws on his suit jacket lapel, then inspecting them. "And they learned the hard way. Which is why I am warning you."

Bunny huffed. "Yer yankin' my chain," he accused. Jack Frost hadn't seemed even remotely dangerous. He'd fluttered about from branch to branch, frosted over some trees, and followed Bunny for a few miles, making banter and some bad puns. Hardly vicious enough to warrant a warning like that.

Punx sighed. "I understand. He's a good kid, easygoing. It's hard to cross him. But, he's not the herald of Winter for nothing. So all the same, it stands:" he repeated, "Do not cross Jack Frost."

Yanking a weed out of the ground, Bunny scowled at the dirt. He shouldn't be so quick to judge. Hidden power was hardly a rare trait in the spirit community. And if Punx was right, if Frost was really the head Winter Spirit after only a century or two of existence, maybe it wasn't a stretch. Bunny tried to picture Frost pitted against the Yuki Onna Empress, turning it over in his mind.

"Why'd he kill her?" Bunny asked suddenly.

"Come again?"

"Why did Jack Frost, allegedly, kill Yuki-Hime?"

Punx's grin was wry and bitter. "Our Jack is a little overprotective," he explained. "Actually, I think you'd approve."

"Why's that?"

"The Yuki-Onna are spirits that use blizzards to kill strangers, mostly children," said Punx. "Including spirit children."

Bunny knew this. He and the Guardians had encounters with the Japanese spirits before. But all the same, his blood curdled in anger. He hated anyone who'd dare lay hands on a child.

"And the Empress made the fatal mistake of kidnapping one of the Little Match Girls. All of whom are under Jack's direct protection." Punx went on. "No one's really sure what Yuki-Hime wanted—to kill her? Eat her? Use the girl's matches to lure more mortal children into her grasp? It doesn't matter, really—the moment she kidnapped the girl, Yuki-Hime was as good as dead."

…So Jack had a soft spot for children. Hm. Bunny half-raised one of his ears in thought. Maybe the bloke wasn't so bad after all.

Punxsutawney drew himself up to full height, about as tall as Bunny's knee, and gave a serious look. "As your advisor, and closest friend," he began, and Bunny was quick to roll his eyes. "I'm giving you forewarning. You will see Jack again. He, for some unfathomable reason, likes you. Try to keep it that way."

"Go shove a stick where the sun don't shine," Bunny grumbled.

Punx gave an exasperated sigh. "See? This is what I'm talking about. Vexing."

Bunny would've responded with a more colorful obscenity, but the Groundhog tipped his top hat in goodbye, and turned to saunter towards the door.

"Remember," Punx called over his shoulder, voice serious as he left. "Do. Not. Screw. This. Up. Jack Frost seems nice now, but he can be downright scary when his little ones are threatened. And I know you'd never hurt them, but accidents happen… and if he gets that mad over little children, who knows what else could set him off?"

Bunny would have blown off the warning, but he couldn't shake the fact that Punx actually sounded sincere. Bunny met Punx's eyes, who tipped his hat one last time and leveled a stare right back.

"Bunnymund," he said, "Honestly, for your own sake — Do not cross Jack Frost."