I really love both Robin and Franky's stories and how they're interwoven throughout Water 7 and Enies Lobby, and I think their narratives really lend to a very beautiful poetic pairing. Their moment on the train was electric, it's hard for me to really explain why that is haha. He's building the foundations for the future and she carries the voices of the past. They've both been broken - both physically and mentally to some degree - and had to put themselves together on their own until they couldn't anymore, and they found a home that they literally get to live their second lives together. Ship or not, I find their relationship very warm and comfortable with one another and that's. Super sweet. Their banter is always funny - her comments never come off as mean or angry, just blunt or playful in her own way. It reads to me like they're very not traditionally married but basically married. They for sure match each other's freaks. Other things like the fact that Franky is kinda built like Saul is some pathological level of sweet to me. Idk, the woman who was called a weapon her whole life and the man who turned himself into one because he loves them so much speaks to me more than a lot of ships can.