Yeah. People tend to assign vice-captain to Zoro, but I don't think that's ever been mentioned in official materials that just label his position as more of just a fighter.
Yeah, people call Zoro vice captain more out of a joke/hype. Oda had the idea of making the sniper be vice captain, a remnant of which can be seen with Usopp joking about it, and Bartolomeo refers to Zoro as vice captain by his own admission, but Oda for whatever reason has never been keen on having Luffy really focus on having a vice captain. Really though, vice captains are usually had for larger crews that need being kept in check. I suppose it’s comparable to having commanders and officers in that Luffy has never seemed keen on organizing his crew like that, since the crew isn’t that big to begin with.
That being said, Oda did have Luffy and Usopp have this little exchange in Chapter 42, which I suppose goes back to the idea of the vice captain taking over a task when the captain isn’t able to, but this hasn’t really been followed up on since.
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