One Piece belongs to Eiichiro Oda
There was no doubt that Luffy loved his crewmates. In fact, they were about ninety-three percent certain he prioritized them over meat. It showed in his unhesitating lunges over the Sunny's railing as Chopper sometimes fell over while they were playing, even though he was no better in the ocean himself. It showed on Robin's birthday when Sanji baked her a special three-tiered birthday cake and he tried his very best not to eat it before she did. It even showed in the late hours of the night when everybody was sound asleep and Luffy would climb out of bed to go keep whoever was on watch some company.
Nobody had any doubts about it.
But the bond between captain and first mate - not all of them understand it but they all agree it is something different.
Those bonds showed in how, even though he was at the opposite end of the ship, Zoro instinctively knew when Luffy had fallen overboard before anyone else did. It showed in his silence while everyone else cried out and protested against yet another one of Luffy's whacko plans. It even showed in the wee hours of the morning, when Luffy would shake him awake and plead with him if he could please oh please go fishing with me there are so many big ones near our boat today but Usopp doesn't wanna wake up yet cos he just finished his watch and he'd grumble and curse but grab the fishing rod from the rubbery hands anyway.
Similarly, the rubber-man's unwavering trust in Zoro to follow along with his crazy plans, pull him safely out of the water and agree to fish at bloody 4AM in the morning can only be reasoned by that bond as well. Next to the delicious scent of meat and the smiles his nakama give him, that is another one thing he can always blindly rely on.