Throughout One Piece's run, Oda has managed to craft some very intriguing character relationships. Some are filled with kindness and love, while others are deeply manipulative and sickening. These dynamic character relationships help to advance the plot of the story, while ensuring that the characters involved are entertaining enough for the audience to care about them.
In One Piece, this usually happens through flashbacks, where Oda tends to like revealing past relationship dynamics before cutting back to the future, as a means of directly juxtaposing the past and the present.
10 LUFFY, SABO, AND ACE
The ASL Pirates are a group of sworn brothers that came together on Dawn Island. This group consisted of Monkey D Luffy, Sabo and Portgas D Ace. The three kids all grew up on Dawn island; Luffy in Foosha Village, Ace on Mt Colubo and Sabo in the Goa Kingdom. The three met when they were fairly young an formed a strong bond. They would adventure all over the island and steal 'treasure'. The bond formed was based on mutual codependence and seeing the brothers grow together was a truly remarkable thing to experience.
9 NAMI AND ARLONG
Nami grew up in Cocoyashi Village with her adoptive sister, Nojiko, and her adoptive mother Bell-mere. For a while, the family lived in peace, but then Arlong came along. A belief that fish-men are superior to humans led him to take control of the Village where he ruled with absolute power, until he was defeated by Luffy. Arlong's relationship with Nami was based on exploitation. All he ever did was take away from her as she labored away in hope of one day freeing her village.
8 ZORO AND LUFFY
To become Pirate King is the most difficult task in the One Piece world. So, in order to reach those heights, pirates must do whatever they can to align themselves with powerful individuals.
It works even better if you can form a mutual bond of trust and friendship with that person, because that ensures that they will have your back in times of need. Zoro and Luffy have shared a special bond ever since they met in Shell Town. Though they hardly ever verbalize their feelings, the dedication and loyalty they have towards each is other is something remarkable.
7 VANDER DECKEN AND SHIRAHOSHI
Vander Decken has always been deeply obsessed with Shirahoshi and, for many years, he's tried to pursue her, despite Neptune's best efforts to keep him away from his daughther. Decken's pursuit of Shirahoshi has often brought about great casualties and destruction to the Fish-Man Island. But despite this, he continues his pursuit. Decken's feelings towards Shirahoshi is based purely on the fact that the mermaid princess can communicate with Sea Kings, an ability he wants to exploit. Thankfully, Decken was beaten and later arrested in the Fish-Man Island Arc.
6 SHANKS AND LUFFY
Shanks and Luffy are bonded by the former Pirate King, Gol D Roger's famous hat. The hat serves as a physical representation of Luffy's promise to Shanks to one day become a great pirate. In the early parts of the series, Shanks acts as a mentor to Luffy and ignites the young boy's passion for adventure. After becoming friends with the Red Hair Pirates, Luffy knew exactly what he wanted to be, the Pirate King. Seeing Shanks' sacrifice for Luffy showed just how much he cared for the young boy and it made for a touching scene.
5 COBY AND ALVIDA
As a young boy, Coby got stuck on Alvida's ship and the pirate forced him to become one of her crew members. For years, he slaved away, listening to her every whim without ever even trying to escape. Alvida was manipulative and abusive towards Coby and, by the time the audience meets Coby, it's cear that he's been verbally and physically abused by Alvida, broken to the point of submission. The series does it's best to play this off but, if one takes the time to look at it, it then becomes obvious how bad Coby's situation was.
4 MINKS AND KOZUKI CLAN
The Minks of Wano have long since been like kin to the members of the Kozuki Clan and, to this day, they retain a strong loyalty towards the Kozuki family. Back on Zou, the Minks were willing to sacrifice their lives and country just to ensure the safety of Raizo, one of Lord Oden Kozuki's allies.
Despite being tortured and poisoned, all the Mink remained loyal to the cause and, when it was finally revealed that this was a known sacrifice, the fanbase could not keep quiet. For weeks, the words "Raizo Dono is safe" were the talking point of the One Piece community, showing how truly powerful this relatonship had grown to be.
3 CAESAR CLOWN AND THE CHILDREN OF PUNK HAZARD
Caesar Clown is a mad scientist and, as such, he goes around doing all the crazy things one would come to expect from an unhinged scientist, such as: making poison weapons and kidnapping children and experimenting on them. Under the instructions of Big Mom, Caesar attempted to gigantify children. This forced the children to grow at an increased rate, which would often cause them pain. To get the children to continue the experiments, Caesar would drug them. This is a truly sickening act. Fortunately, the children were later taken to Vegapunk who might be able to return them to their former sizes.
2 CORAZON AND LAW
Corazon and Law shared a very special bond. After orignally losing his family in the tragedy of Flevence, Law evetually met Corazon, who he would grow to love. After learning about Law's sickness, Rosinante searched all over the world for doctors who would be able to treat Law's sickness. However, instead of treatment, they were met with disgust, which often resulted in Corazon burning down the hospitals. The bond between Law and Corazon was natural and authentic, which made it so much more appealing.
1 CELESTIAL DRAGONS AND HUMANS
The Celestial Dragons are direct descendants of the rulers of the twenty kingdoms that formed the world government. As such, they view themselves as very noble people, even going as far as treating themselves as if they are genuinely the gods of the world. This is the prevailing mindset of most Celestial Dragons, leading them to treat other humans as inferior. The Celestial Dragons view everything outside themselves as their property which they can do anything to. This lack of regard for others is simply appalling.