Franky had explained that it was technically stretching. Stretching was very important, he'd explained, because it helps keep both biological and mechanical components in peak condition. It was part of why he was so strong, he'd said. Everyone ought to stretch if they want to be as strong as Franky was. He'd even gotten a slightly perplexed Zoro to verify this for him.
It still looked like dancing to Chopper.
Robin told Chopper one day during Franky's stretching routines that yes, it was important to stretch, and that that was a good excuse, but Chopper hadn't been quite sure what she meant by that. That was okay, though. He would never be bored as long as he had all of Robin's little mysteries to work out.
Chopper did like to watch Franky stretch, though. It was…interesting. There wasn't a particular pattern to it, not that Chopper could see, but there was definitely some sort of system. Apparently, everyone had their own little mysteries.
Love, Robin had once told him, was the biggest mystery. There was no rhyme or reason to it, no room for logic or simple equations. It was something that flowed, that moved, that constantly changed; it could not be tracked or charted. There was no recipe for love, and it could not be mapped; it could not be won by a blade and it held no room for lies. It was, however, a flexible thing (emotionally, not physically, but Chopper thought that the point still stood).
Chopper had also learned, from Robin and also from observation, that there were different types of love. There was the love between all of them, the love of nakama, like a web holding them together, and then there was that certain other type of love that Chopper stood outside of, as did Robin, and now, Franky.
It was the sort of love that compelled Sanji to drag a semi-conscious Luffy from the water and curse him for causing Sanji to ruin his new shirt in one breath and ask him if he was all right or needed anything in the next.
It was the kind of the love that allowed Nami and Usopp to pull off a subtly masterful prank that resulted in Zoro waking up to a water balloon filled with blueberry syrup to the face with the culprits literally nowhere to be found.
The love that had Sanji and Zoro fighting like stray dogs one moment and sitting together in companionable silence the next, and that made Nami laugh when Luffy plopped his hat onto her head and grinned, and that saw Usopp telling Sanji wild and unbelievable stories that made him smile while he cooked supper.
That was the kind of love Chopper had for Robin, he supposed, and that she had for him. Their love was the kind in which Robin read her books aloud while Chopper listened in fascination, and that caused Chopper to work that much harder to find a cure for all diseases, and that kept them both up at night, watching the stars together. They made each other happy, and they solved life's mysteries together.
Chopper wondered if Robin could help him solve the mystery that was Franky.
He seemed so obvious, so blatant, as if he was hiding nothing; all of his actions served to present himself to the world as if to say "Take me or leave me." But Chopper knew, because he could be quite intelligent on his own if need be, that if he were to ask Franky about his past and his family, he would receive a answer that was defensive and avoidant in the loudest and most forthright manner possible.
He also knew that when Usopp told story of the beautiful maiden in distress that he very nearly did not manage to rescue, Franky did not, in fact, have something in his eye. Nor was he simply plotting how to best repair Luffy's latest architectural mishap when he leaned on the railing and looked far out to sea.
Everyone has mysteries. Franky's mysteries were trapped deep under layers of bravado that had been building up for a lifetime, and that wouldn't be peeling away any time soon. But that was okay. Chopper was patient. Chopper was good at observing quietly and waiting for abnormalities in a pattern to appear.
And he would find out eventually, he was certain, even though Franky was one large abnormality who didn't have a pattern.
He did have a system, though. Chopper could see it, and he wondered if Robin could see it, too; if she was looking for it. She must be looking for something, what with the way she watch him stretch, or dance, or whatever he was honestly doing.
Chopper sat next to Robin on the deck one day and watched with her. It was, they both decided (with a glance at each other, they way their mutual realizations tended to be made), definitely dancing. One did not stretch for a crowd. It was not the sort of activity that is done as a performance. Dancing, however, is.
As he watched, Chopper wondered if Robin liked to dance. He wondered if he, himself, liked to dance. He had never tried it before. He looked at Robin, inquiring, and she smiled at him; a smile of mysteries revealed. And Chopper smiled back.
"Franky?" Chopper asked, and the cyborg looked over his shoulder, halting mid-pose to accept the forthcoming question. Robin stood beside the reindeer, smiling a small, patient smile, with her hands folded in front of her. "Can we join you?"
There was a long pause as Franky considered this. He dropped the pose and turned to face them, wearing an expression that could only be described as guarded, and uncharacteristically so. This was followed by a nearly unnoticeable split-second of vulnerable that was chased away by a broad grin.
"Sure," said Franky, and then he paused, because there was something he wasn't quite ready to give up, but then… "If you know how to dance."
"You might have to teach us," Robin said, still smiling. Franky grinned all over again, slow this time, like dawning realization.
Chopper knew that they all had things to learn from each other, and a lot of mysteries to solve, and he knew that it was going to be a journey finding them all out.