Okay I just found out that wrestling is something otters love to do, so maybe you could incorporate that into a chapter with the moss-rat? Love the fic, it's super cute! Prompt from twiligertumbling

Another thud on the deck as yet another nakama fell down with either a laugh or a shriek. Nami and Robin were tending to the orange trees and chuckling as the dark furry blur of Zoro's body shot across the deck and bowled over into Luffy and took the captain's legs out from under him and sent him tumbling to the grass.

Chopper had said that Zoro needed to be played with in his new body or else he'd get fat or ill. He needed to be active for at least an hour a day and who better to get a game going than Luffy? Robin had pointed out that in her numerous studies she had learnt that otters were fond of wrestling one another. She assured Usopp that though Zoro may be coming across as agressive, it was only play fighting that was not to be taken seriously.

The mossrat was practically having the time of his life, chittering excitedly as he scampered after the crew mates one by one. Bam! He knocked Brook down. Bam! Usopp was down. Bam! Chopper went tumbling. All three of them laughing hysterically.

Franky soon emerged from the lower part of the ship and Zoro wasted no time in trying to knock him over too. The cyborg looked curiously at the little otter gambolling into his legs over and over but to no effect. Once he realised what Zoro was doing, he faked falling over anyway much to the mossrat's delight and off he ran again, paws thumping on the wooden decking.

Sanji however, did not find it even remotely amusing when he opened the galley door to call for lunch and was greeted by a face full of otter.

He toppled backwards into the doorway, landing on his rear, and Zoro squeaked triumphantly as he neatly dropped from the cook's face and into his lap where he began his furious assault on Sanji's jacket buttons with his teeth, grunting repeatedly. The blond seemed to overcome his moment of being stunned and glared at the furious fur ball in his lap, grabbing Zoro by the scruff of his neck and lifting him up until he let go of the button he was gnawing and held him away at arm's length as he got to his feet. Just another thing he'd have to add to the 'Beat Zoro's Ass For Later' list he had going on mentally.

Zoro made a funny noise and Sanji saw the discomfort in his little angular face and eye. He sighed and held the mossrat properly in his arms, bringing him against his chest. Luffy was laughing, "He got you good, Sanji!"

The blond blinked. So Zoro had been playing? He hadn't just turned feral then? Sanji had just assumed the shitty rat was playing up to piss him off and began to feel a little guilty for having got the wrong end of the stick like that. Subconsciously, his free hand rubbed at where he'd grabbed Zoro roughly as some form of apology that he didn't realise he was giving. The otter chirped and Sanji moved his arms away as Zoro began to climb up his chest to perch on his shoulder. He smiled, "Yeah he got me. Nami-swan! Robin-chwan! Lunch is ready!"

"Oh boy! Lunch!" Luffy bellowed but Sanji blocked him with a single held up leg.

"Ladies first, you manner less bastard," He said curtly, letting the hurricane of their captain through as the two women sat down and began to eat.

Zoro clicked his tongue, still sat on the cook's shoulder patiently. Sanji turned his head to look at him, "We'll play later... if you want..?" He asked awkwardly. He honestly never thought he'd have to say something like this to the mossball ever in his life. But Zoro chirped more than happily and Sanji passed him a cucumber slice from the chopping board which he devoured eagerly.

The blond was beginning to get concerned. Everyday Zoro was acting more like a pet- like an actual otter- compared to how he used to. He looked from his plate to his nakama on his shoulder and couldn't help but think that surely these actions couldn't be a good sign.