He kinda parallels Sanji when you think about it too. Sensitive guy being forced to try and become an emotionless weapon, a robot with no feelings and free will, like Judge was trying to do him and mostly succeeds with his siblings too especially.
Kaido and Ororochi did something similar with the Smile fruits too. Doflamingo and Sugar with turning people into toy puppets too.
Its bad enough that Pudding has been kidnapped but if something fatal happened to her or if Nami or Robin got severely injured at least, something closer to permanent or fatal too, I could see Sanji finally snapping and regretting he didnt become the monster he needed to be, thus Sanji could a current parallel to Kuma or something.
Theres also Franky gradually making himself more and more of a robot, a machine and losing his humanity but Oda is not even exploring that in the MOST relevant and important arc to that and Franky than ever will be in the series either, sigh.