not ‘zoro is the first mate/vice captain of the straw hat pirates because he would take over for luffy if something happened’ because 1) zoro has never shown any desire whatsoever to be a captain 2) even if he did none of the other straw hats would take him seriously in that capacity but most importantly 3) the straw hat crew flat out DOES NOT EXIST without luffy as its captain so arguing whether or not zoro would take over is a moot point to begin with—but rather, ‘zoro is the first mate of the straw hat pirates because he is the only one amongst them who isn’t afraid to tell things exactly how they are when the crew needs to hear it, and that is a critically important counterbalance needed with a captain as reckless as luffy’. zoro is the first mate of the straw hat pirates because he doesn’t believe in the impossible but he DOES believe in the impractical, and being able to tell the difference between the two is a vital skill for encouraging luffy’s best instincts but also reigning in his worst tendencies. zoro is the first mate of the straw hat pirates because he’s just as big a dreamer as the rest of them, but he will also remain steadfast in his duty to keep the others safe, even at the cost of his own ambitions. because what is the point of being a dreamer if he can’t protect his captain and his crew?
okay sorry i need to add to this because people are always making fun of the fact that zoro and luffy share the same brain cell and it’s like no you don’t UNDERSTAND sharing the brain cell is an ESSENTIAL PART OF THE DYNAMIC because sharing the brain cell means that zoro knows EXACTLY what luffy is thinking and also EXACTLY when he needs to pull luffy back!! if they didn’t share the same brain cell the dynamic wouldn’t be nearly as cohesive!! to quote @prophecydungeon it’s realist-and-dumbass vs "i don't care if it's realistic, i'm making it happen"-and-dumbass but either way the dumbass part is a CRITICAL COMPONENT.
@likorys-shimenawa so, yes and no! i was actually just talking with someone about this last night and imo sanji and luffy do NOT share the same brain cell in the way zoro and luffy do because unlike zoro and luffy, sanji is never heedlessly reckless the way that they are, and i think that recklessness is a key component of the dumbass-for-dumbass dynamic that zoro and luffy have going on. what sanji and luffy DO share however (and what zoro critically doesn't) is an emotional core/bleeding heart. sanji and luffy are both very much driven by emotion in a way that zoro isn't and they're both willing to override what they feel is practical in favor of doing what they feel is right, and sometimes, that's actually the better call!! if zoro is the counter weight of practicality on the right side of luffy, then sanji is the counterweight of emotionalism on the left side, and both of them are key to elevating luffy to the heights he's managed to obtain. the main reason sanji wouldn't get the first mate title (imo at least) is that he already has the title of cook, which on luffy's crew is (let's be real) just as if not more important lol than the idea of being first mate anyway.
but wait, we can go even further!! because while zoro and sanji don't share a brain cell and they don't share a bleeding heart (which is not to say zoro doesn't care, just that he's usually coming at it from a very different angle than sanji is), what zoro and sanji DO share is... pretty much everything else, actually. they're both protectors, they're both willing to lay down their lives for the rest of the crew, they will both stand unflinchingly by luffy's side to lift him up without really wanting any of the glory for themselves. and more than that, they make up for what the other lacks in a way that completely rounds out a whole and makes them a more perfect unit together than apart. zoro is steadfast where sanji is fiery, and sanji is tender where zoro is blunt. zoro is more proficient in armament, sanji excels in observation, and if sanji doesn't gain conqueror's haki or something equivalent by the end of the elbaph arc i will eat my shoe. if one of them is attacking head on then the other is holding the back line, and both of them are perfectly aware that no matter what, luffy comes first. zoro can be objective in ways that luffy and sanji can't, while sanji can be cautious in ways that luffy and zoro can't (or won't), and both zoro and sanji can be realistic in ways that luffy refuses to be unless he's forced. luffy's dynamic with both of them is important, but so is their dynamic with each other because if that part wasn't there, then their own parts in being a counterweight to his antics wouldn't work either.
anyway, in conclusion: LUFFY+ZORO+SANJI IS A BEAUTIFUL TRIUMVIRATE AND IT CAN'T NOT BE A TRIUMVIRATE!!!! NONE OF IT WORKS WITHOUT THE DOUBLE COUNTER WEIGHT!!!! YOU CAN'T HAVE A TRIUMVIRATE WITHOUT BALANCE AND YOU CAN'T HAVE BALANCE WITHOUT THE TRIUMVIRATE!!!!!!! A TRIANGLE CANNOT EXIST WITHOUT THREE SIDES AND A BIRD CANNOT FLY WITHOUT TWO WINGS TO HOLD HIM ALOFT!!!!!! AAAHAHAHAAAAAAAAHAHAHAHHAAAAAAAA
