Okay, This is a chore, But decided to finally do this. I have long wanted to write my thoughts about the relationship between Luffy, Zoro and Nami. I just wanted to collate all their moments in one place.
In Ancient Chinese Taoist philosophy two forces yin (from the ancient Chinese word for shady) is represented by the tiger and yang (from the word for bright) is represented by the dragon. Male traits are yang, and female traits are yin. Yang qualities are active, while yin qualities are passive. Everything in the universe results from the interaction of yin and yang and the balance between them.
The above colour spread comes to mind, you can see that Luffy is balancing himself on the tiger and Dragon. Tiger is being represented by Nami and Dragon is being represented by Zoro, Traditionally the tiger has been orange (Nami's orange hair) and The dragon has been green (Zoro's green hair). In my opinion, Nami is the feminine (Yin) to Luffy's masculine (Yang) and Zoro is the masculine(Yang) to Luffy's feminine(Yin).
Nami has always been the epitome of femininity, she has a very motherly nature towards kids, this is also shown by her behaviour towards Momo and Tama etc. Not to forget Nami takes the passive role in the crew, managing the household expenses, navigating the crew through the waters, She is in certain situations more emotional than Luffy and Zoro. She will go to any lengths to protect the ones who are close to her e.g her stealing from pirates and serving under Arlong, this explains her shady nature as yin energy. She is more grounded in reality as opposed to the crew powerhouses Luffy, Zoro and Sanji.
Zoro on the other hand is the embodiment of bushido/samurai, Bushido being the benchmark of masculinity in Japanese culture. He has a great ambition, is honourable and always ready to protect the ones who are weaker than him, He wants his name to reach the heavens (dragon is connected with heaven). Interestingly many of Zoro's attack has dragon in it. Zoro being the combatant of the crew plays more active role in the crew. He is honest, very straight forward and to the point unlike Nami. Zoro acts as more authoritative figure in the crew when time requires.
I see Nami as the perfect feminine Yin representation and Zoro as the perfect masculine Male representation in the manga , I want to discuss the relationship between these three further.
From the start , Oda has shown Zoro and Nami by Luffy's side, In east blue, Zoro fights the strong opponents with Luffy and Nami steals the treasure, navigate the sea etc.
Fast forward to the Whiskey peak, when the straw hats were being conned by bounty hunters, only Nami and Zoro stay awake, Nami making a deal with Vivi and ultimately an emotional bond with Vivi and Zoro protecting the crew against hundred of bounty hunters.
In Alabasta we see Zoro being the level headed person and heeding to Luffy's commands and Nami comforting Vivi when they left Luffy to fight Crocodile back.
In Mock Town, Oda decided to introduce one of the major villain when only these three were present, this says a lot about the importance of this trio.
In Skypiea, we see how oda again highlights different perspective of Zoro and Nami about God, as opposed to Luffy's "don't care if you are God" attitude
Nami and Zoro both support Luffy side by side in their own ways to help him go upwards to beat Eneru.
Water 7 is another key arc for this trio, Luffy was in verge of losing two of his crew mates. Both Zoro and Nami have different opinions. Zoro was sceptical of Robin and didn't want Usopp to come untill he apologized to Luffy. Nami on other hand was bounded by her emotions. Luffy took Zoro's advise in this matter.
This is in direct contrast to Zou, where Luffy decided to take Nami's side , again the reaction for Sanji leaving is highlighted for Zoro and Nami and how vastly different they are.
In Dressrosa, Zoro accompanies Luffy all the way to the 4th floor, helps him fight Doffy's underlings and stops pica on his path, And In final fight with Doffy, He decides to take lead to stop the birdcage.
This is similar to the situation in WCI where Nami helped Luffy pave his way through the seducing woods, helped him fight cracker. During his fight with Katakuri, she took the lead and asked rest of the crew members to break all the mirrors in the ship.
As For Thriller bark, Zoro, Luffy and Nami all get something from there which becomes a plot point later on. Luffy got the armlet which helped him free Ace, Zoro got shusui which helped him gain Enma in Wano, Nami got Lola's mother's (Big Mom's) vivre card which helped her save Luffy's life later on.
Okay, I am tired now, will add other things later on.
@Zoro D Goat