Zoro's lack of interest could mean he's aromantic or asexual, but it could also mean he just hasn't found the right person yet. While Zoro has yet to express any romantic feelings towards anyone and Sanji has expressed his to literally every pretty woman, this doesn't stop the ZoSan Shippers from hoping that one day their pairing will become canon. All of these little moments add up in the eyes of the fans. There's a moment when the two are washing dishes together and Sanji calls Zoro by his name instead of "Moss Head." There's a moment in one of the filler episodes where the two fall asleep on a rug next to each other - in fact, they sit together in many episodes and manga panels. One Piece fans look for little hints and moments that could further their ship, no matter how minute. RELATED: Why the Most-Hated One Piece Character Still Enrages Fans There's even a Fandom Wiki page for the pairing. Though they butt heads, they have shown time and time again that they genuinely care about the other's wellbeing. In their eyes, their bickering and name-calling simply hides their true feelings towards each other. Their mutual animosity has fanned the flames of romance in the eyes of ZoSan shippers. While they rarely see eye-to-eye, they do back each other up and care about their crew - which includes each other. They butt heads often and call each other names. While Sanji and Zoro aren't exactly enemies, their actions towards each other aren't particularly friendly either, especially not when they first met.
One of the most popular shipping tropes is the " rivals to lovers" trope. Many times, pairings fall within a certain trope, like one character will be overprotective while the other will be more laidback. This is partly due to a lack of accurate and meaningful depictions of same-sex couples in media that viewers can see themselves in. The most popular type of pairing among fans is often same-sex couples.