Arthur Nightingale/Personality and Relationships

Personality
Although he's known to be a violent fighter, Arthur's actions tend to be for the best. He has a very poor sense of direction, at times asking Marine for help (even though he is a wanted criminal). Arthur lives for battle and enjoys a good fight more than anything. He even holds back in an effort to make any fight last longer. He also claims that injury and death are nothing but the price one pays for a good fight. Despite his being the most blood-thirsty Pirate of the New Eleven Supernovas he can show mercy. He has his own code of ethics, which is different from the rules and regulation of World government.

Despite his aggressive nature, Arthur is very perceptive in battle. He is seemingly aware of any potential danger to his person and can immediately react to it. He is also shown to be analytical, able to quickly deduce the basics behind an opponent's technique

Arthur has also shown a sense of honour, as seen after his freedom when he expressed disgust about the idea of working for anyone who would stoop down so low as to use the dead as their tools after hearing about Gekko Moriah Presumed Death, in the meantime making sure his freedom was permanent. His sense of honour is extended even further when he pleads with the Mayor of the town to allow him to leave to prevent any damage to the town that helped him heal his wounds.

Arthur also strongly believes that fun comes before working. In every battle, he tries to get as much enjoyment out of it as possible. One example is when Arthur sends his First Mate, Ren, to fend off the Bounty Hunters that were chasing after him, as he was the strongest fighter who wasn't busy, or rather, busy having fun. During his free time, Arthur always watches the clouds (a habit he picked up from Calico). He doesn't have a particularly favorite dish, but he particularly hates Sushi.

On multiple occasions, Arthur can appears to be indifferent, caring only for a few things around him. He spends a considerable amount of time mocking and/or causing trouble for the Marines. Despite showing initial dislike towards his Father, Arthur has grown fond of him, and is willing to risk his own life to protect him.

Calico Kidd claims that Arthur is a prodigy at the art of murder, as he has a habit of chopping off his victim's limbs before beheading them. Arthur, despite addressing him with the honorific term "Nii-Sama", wants to defeat him, noting to his ex-crew that he will one day make him into "Fox Coat" (a reference to Calico's Fox Devil Fruit) before disbanding his crew.

Befitting his status as a prodigy at the art of murder, it appears that Arthur has a certain love for killing, but he refrains from doing so at his Grandfather's request. However, there are several occasions where he has killed people when he believed that they were worth living. Arthur has been shown to have thoughts such as "just this once" and "he'll forgive me". However, he was noticeably upset that his grandfather killed several Pirates during the meeting in Alabasta, pointing out how many times Allen had told him not to kill anyone. He was described to have a belligerent personality.

It seems that Arthur sometimes contradicts his own logic in fighting. On the one hand, Arthur wishes to increase his own personal power. On the other hand, he conceals his strength to enjoy a fight for as long as possible. Irrational to a certain extent, Arthur is one of the most complex characters to sail the seas, as he exhibits a wide range of traits, being: lethargic, bloodthirsty, rebellious, empathetic, and wise.