One aspect of ZoSan that Westerners may not get the full nuance of is the concept of “うちの”, literally “of our/my household”. There’s a reason why the EA fandom (mainly Chinese from my POV) disproportionally ship ZS over other ships, to the point where even dudebros hop the joke.
So there’s this Chinese saying that means “be strict to yourself but lenient towards others” which is seen as model behaviour for respected individuals. I don’t know if there’s an equivalent idiom in Japanese but both Koreans and Japanese hold similar attitudes towards treatment of self vs treatment of others in society. Here’s the fun part: thanks to collectivist culture, one’s “self” extends to your immediate family too. Since you’re seen in conjunction with your family, if you’re head of the house and your “inferiors” misbehave in public, it reflects badly on you as a person. That’s why strict parenting is more normalised in EA culture, because controlling how your kids behave is more or less the same as controlling how you yourself behave. This is also related to how tough love is a more common form of affection in EA families, there’s a sentiment of “being able to be mean to you means we’re close, being too nice means I see you as a stranger.”
You might now see how this relates to the Strawhats in general (see: Nami beating up members for acting out of line). Sanji is a funny one coz he was sort of a maternal figure secondary to Nami early on in the series. Women aside, there’s a difference in how he treats men on his crew and “outsiders” (e.g. Ace). He’s actually not rude towards men, it’s just that we predominantly see his interactions with the crew! Since his crew is his family, he can be strict with them like how he’s strict with himself.
How does this relate to ZS in particular? Well, it’s because Zoro is closest to him on the self—others sphere. Luffy is his captain so despite the usual bickering he has to obey him to some degree. Usopp and Chopper are younger and weaker, so Sanji has a responsibility to take care of them and show generosity as an “elder”. Franky, Brook and Jinbe are way older than him so there has to be some degree of respect when interacting with them. Nami and Robin are Women. This only leaves Zoro, who is his equal in both age, power and hierarchical position on the crew. Essentially, Sanji has every right to hold Zoro to the exact same standard as he would himself. And given that Sanji is extremely harsh to himself, he’s harsh to Zoro too.
This is why there was virtually no discourse over the “Sanji calls Zoro a liability” moment in the EA fandom. The unspoken context was that Sanji was apologising to Jinbe for Zoro, who wasn’t performing his best. And since Jinbe is relatively new to the crew and also much older than Sanji, it feels like a mother/wife apologising for her son/husband?? It’s giving “I’m sorry my Zoro embarrassed us”?? It’s giving “Zoro is my responsibility”?? On the flip side Zoro absolutely does this to Sanji too. I can’t name a specific anime moment but in one of the mobile game collabs he said something like “sorry our cook caused trouble for you”. The specific wording was うちのコック. (They both think they’re managing the other lmao I hate them)
Tldr: Zoro and Sanji see themselves as one household unit 😭 hence the bickering and bluntness and lack of pretences in general.
