Khanjikhan was Nadakhan's father. He disowned his son after he left Djinjago to explore Ninjago as a pirate. Nadakhan never saw his father again after he was trapped in the teapot by Soto. After he was freed, Nadakhan went back to see his realm was falling apart. Khanjikhan met his son and reflected on how fitting it was that he returned after his home was dying. Nadakhan reconciled with his father long enough for Khanjikhan to bestow the Djinn Blade and the task of avenging their world. Nadakhan accepted and began terrorizing Ninjago to avenge his father's death and to rebuild Djinjago.
An unnamed Djinn was Khanjikhan's father and Nadakhan's grandfather.
It is unknown if he lived long enough to know his grandson but it appears Nadakhan was aware of his grandfather obtaining infinite wishes and respected his legacy.
Dilara joined the sky pirates in their early days and eventually fell in love with Nadakhan. But after a battle between Captain Soto and Nadakhan, Nadakhan was trapped in the Teapot of Tyrahn. Dilara eventually died before Nadakhan escaped and he was devastated to learn of her demise.
Nadakhan initially mistook Nya for Dilara but he developed the plan to marry her in order to gain the power of infinite wishes. After doing so, he brought Dilara's soul from the Departed Realm and had her possess Nya with the lovers happy at their reunion.
Flintlocke is the only person Nadakhan considers a friend.
In their reunion, the two were pleased to see one another after their banishment. Eventually, Flintlocke attempted mutiny and helped the Ninja defeat Nadakhan.
The Ninja are Nadakhan's main enemies.
Nadakhan learned of their threat when researching the city history archive. For that reason, he impersonated them and framed the ninja for crimes they didn't commit and was pleased to hear they were locked away in Kryptarium Prison. He gained a vendetta against them when learning of the destruction of his world, which occurred because of the ninja's victory over The Preeminent and destroyed the Cursed Realm (the twin realm of his).
After the Ninja escaped, he sought them out to trap them in his sword and get stronger. He played on Kai's heart for knowledge on his father before trapping him. He found a worthy adversary in Zane because of his strategy and noted how he gave him a challenge until he defeated him by deleting P.I.X.A.L.. His main arch-enemy of the group was Jay played on Jay's love for Nya but was unable to get him to break. He also captured Nya and married her to gain infinite wishes for himself and had the soul of Dilara possess Nya.
In the end, they stopped him from destroying Ninjago at the end of season six. Nadakhan's actions were undone by Jay's final wish to restore Ninjago that caused Nadakhan to be trapped again. It is unknown if the ninja have regained their memories of him, since they have experiences deja vu on the matters.
Nadakhan has had a long history with Soto.
Many years ago, Soto attacked Nadakhan and Nadakhan was trapped in the Teapot of Tyrahn while banishing his crew. Nadakhan eventually captured Soto's ship, Misfortune's Keep and used it as his base for the Sky Pirates.