They were always at each other's throats. Always fighting, always arguing.
They knew how to get on each other's nerves better than anyone else in the world. Sanji would insult Zoro's intelligence daily.
Zoro would invent new insults every day, among which his favorites seemed to be 'dartboard brow,' 'ero-cook' or 'dumbass cook.'
It irked Zoro that Sanji was always drooling and flirting with Naru and Robin. But...
just why did it annoy him so much? He usually tried to remain stern and severe, and sure, he could lose his temper, but never in the way he did around Sanji.
Zoro made a point to remain distant from the rest of the crew, but though he sometimes failed, especially around Nami or Luffy, it was Sanji who got the worse of him out.
Was it because he was trying to deny feelings lurking just below the surface? Was it because there was something about that blonde idiot that got him bothered in ways he couldn't understand?
Was it because he was jealous each time he drooled over Nami? It was easier not to think about it; it was easier to just fight with him and call him names.
It was better than admitting he might like him in more ways that Zoro would ever dare think about!