Bunny couldn't remember where or when the idea first came to him. Maybe from watching Jack play with a group of penguins, cuddling with a few of the chicks, or perhaps seeing a polar bear dive into icy water to catch a fish. Or maybe, just maybe it was the way Jack couldn't quite hide his hurt and disappointment when Bunny had to pull away from him, his teeth chattering, skin turning blue under his fur.
Whatever the trigger there was no delay between idea and implementation. A thick soft undercoat grew and fluffed out his fur as his overcoat grew long. A layer of insulating fat obscured his sleek muscles. North teased him about eating too much carrot cake. Tooth probably never even noticed, as long as he didn't make changes to his teeth. Sandy simply gave a happy approving smile.
Jack never said anything, he didn't need to. Content to simply lie there, wrapped in Bunny's arms. Perhaps just as content as Bunny was to have him there, breathing in the boy's scent, stroking soft silky hair. Just being together for hours on end, and Bunny marveling at how just a few small changes made for all the difference.