The reason is because Zoro understands exactly what Luffy means just by a look or by even Luffy calling his name. Luffy goes to Zoro the most out of anyone on the ship even for the smallest of things. He has proven to understand Luffy the first time when they met each other.
That said, there is one crew member who stands above the rest in terms of loyalty to Luffy: Roronoa Zoro.
Zoro trusts Luffy implicitly and always follows his decisions whatever the consequences, acknowledging it as a captain's decision, which a crew must carry out without question. When Zoro first joined Luffy, he made it clear that he would turn on or even kill his captain if he ever stepped between him and his dream.
Zoro is perceived as the vice captain of the Straw Hats. He is arguably Luffy's most loyal crewmate. He has displayed the most respect and dedication to Luffy by following his orders, proclaiming promises, and being the most vocal about Luffy achieving his dream of becoming the Pirate King.
The friendship Luffy shares with Zoro is something he cherishes and was overjoyed when he was reunited with him in Wano, launching himself towards the swordsman and hugging him. Zoro returned the sentiment and greeted Luffy with a big smile.
At least two have fallen in love with him, Alvida and Hancock, whilst another two have become enamoured with him, Rebecca and Shirahoshi. Nami, Robin and Vivi all share close and deep bonds with Luffy and have become some of his closest friends.
Out of all the Straw Hats, Usopp is easily the least loyal. Not only did he nearly abandon the heroes amidst their darkest hour at Dressrosa, but he also fought Luffy directly for the rights to the Going Merry.
Kuina is the greatest influence in Zoro's life. Kuina was Zoro's childhood rival and friend. She was a skilled swordsman and shared the same goal as Zoro of becoming the world's greatest swordsman. Kuina envied Zoro for his masculinity, but Zoro dismissed her beliefs.
It is the sequel to 1998's The Mask of Zorro; Antonio Banderas and Catherine Zeta-Jones reprise their roles as the titular hero and his spouse, Elena, and Rufus Sewell stars as the villain, Count Armand.
Jong-hak Baek: Nami's Husband.
Who is Nami's crush One Piece? Nami cares about Luffy deeply and will often hug or hold onto him when she is scared or depressed. Their relationship is consistently presented as positive and affirming, an example of two people with compatible dreams and different temperaments working out conflicts as equals.
Highest: Jimbe. Ever since this character has brought into OP world there was no 1 moment when he didn't respected luffy. Lowest: Usopp.
Zoro x Hiyori
They shared intimate moments and Zoro might even find a sense of belongingness when he's with her. Throughout his tedious journey, Zoro met a lot of potential partners but the connection he seems to have with Hiyori seems special as Wanokuni has immense influence over Zoro's life.
Now, in his profession and to fulfill his dream, perfect eyesight plays a major role. So this theory suggests that Mihawk noticed this and scarred Zoro's left eye, which is supposedly suffering from ocular dominance, and instructed Zoro to keep it shut until he trains his right eye to become strong enough.
Luffy will never find out about Zoro's sacrifice in Thriller Bark. Sanji is the only person in the Straw Hat crew who knows about this ordeal. Zoro took all of Luffy's pain despite having several injuries himself. The swordsman was barely alive when Kuma was done with him but still kept standing.
Who is most likely to marry Luffy? 1 Boa Hancock She is cruel and manipulative. Boa uses her beauty to gain others' forgiveness after acting inhuman. Still, Boa Hancock is the one who most likely will end up with Luffy because fans are still excited by the idea.
His father, Roronoa Arashi, was killed by pirates and his mother, Tera, died of illness when he was young. Zoro is a descendant of the Shimotsuki family of Wano Country through his grandmother Furiko, the older sister of Ushimaru, the daimyo of Ringo who is Zoro's great-uncle.
Charlotte Pudding is a supporting character from the anime and manga series, One Piece. She is Charlotte Linlin's 76th child and 35th daughter, and one of Charlotte Linlin's favorite daughters. She was arranged by her mother and Vinsmoke Judge to marry the Straw Hat's cook and Judge's estranged son, Vinsmoke Sanji.
It's rare to see Zoro get close to another woman that isn't Nami or Robin, so fans welcome the idea of a ship between him and Hiyori. Their personalities are complete opposites, but there is a strong bond between them. Their banter is also a joy to watch, and fans are eager to see more of it.
Tsundere - Zoro has a heart of ice, as he does not show his emotions at all. Although he is characterized in this way, he cares a lot about Nami.
Robin also seems to be very devoted to Luffy, as he is the only person whom she wants to get stronger for. This shows how great her dedication to her captain has become after being rescued from Enies Lobby. Upon learning of Ace's death, Robin was very shocked and became greatly concerned about Luffy's wellbeing.
One of my biggest pet peeves is the idea by some that Luffy's rejection of Hancock — the most beautiful woman in the world — is a consequence of him being childish, stupid, and/or ignorant of love and marriage. What Oda has done with Hancock is brilliant.