""Right now, I'm letting you live. And I'll continue to keep you alive... until you've grown enough to become worth killing. ♠""
Hisoka is shown as entirely self-serving, self-absorbed, and selfish; he does whatever he likes as long as it pleases him in some way. His insatiable love for spilling the blood of powerful fighters in combat and his enjoyment of extreme pain while doing so fuels his seemingly sadomasochistic desires. In order for them to grow to their full potential (so as to improve the pleasure of killing them later), Hisoka allows the main protagonists to live in situations wherein he is easily able to kill them. Likewise, he grows excited to meet any new people he deems worthy of fighting or anyone with potential to be a good fighter and entertain him in the future.
With his manipulative and self-centered nature, Hisoka is essentially a sociopath. While he does like Gon, Killua, and many others, he has stated that for him what is valuable one day could easily become trash the next, and he will not hesitate to kill anyone should they not meet his standards. He does not care for what has happened in the past, as he is only interested in what could be amusing to him in the future or present. While Hisoka's nature tends to be malevolent, he isn't an indiscriminate killer. He has no problems killing anyone regardless of age or sex; however, he only kills people who are in his way or those he deems "worthy." As such, his character is more simply amoral than flat out evil. He even assists the protagonists if there is "fun" in doing so or if it will make them stronger leading to a more entertaining fight in the future. Above all else, Hisoka cares only about having fun and a good challenge which may or may not involve killing people. He has a nasty habit of skipping out on Spider meetings.
Hisoka could be described as pansexual, but in a very deranged way: he is attracted to powerful fighters, or people who have the potential to become so, be them men, women or children, and his desire is expressed through barely repressible murderous tendencies.
Hisoka often exhibits androgynous characteristics throughout the series, manifested in his wearing of "women's" shoes and using an alluring speech style typically reserved for females in Japanese. In the manga, he ends nearly every sentence with a suit symbol.
- In the official databook, his name is "Hyskoa."
- Hisoka's name written in Kanji (密か) can mean "secretly."
- In the Latin American dub, Hisoka speaks with a French accent and his name is pronounced as "Isoka" (with a silent H). In the Brazilian dub, the French accent is kept, but his name is pronounced normally.
- In the Indonesian dub, Hisoka is pronounced as "Hyosoka" for unknown reasons.
- Hisoka's Nen abilities are named after his favorite candy and chewing gum brands.
- The name of his primary Nen ability may be a pun on the extreme sport Bungee Jumping.
- Also, the second name of Bungee Gum, Elastic Love, may be seen as a reference to Hisoka's personality: the ease with which the gum is attached and detached to someone mirrors the interest that Hisoka has in a person, which can be extremely deep and still end at any moment.
- A major source of inspiration in the creation of Hisoka is probably popular DC Comics supervillain The Joker. Both of them:
- are based on the playing card of the Joker.
- wear make-up and have dyed hair (although this is the Joker's true appearance)
- are serial killers with irresistible murderous tendencies and a long list of victims.
- are sociopaths who refrain from forming conventional bonds; in fact, although they appear to be close with another character of their respective universes (Harley Quinn for the Joker and Illumi for Hisoka), they do not hesitate to take courses of action that would damage them.
- are obsessed with the main character of their respective series; specifically, with the ones who can challenge them. At the same time, the hero himself (Batman and Gon) harbours complex feelings towards them.
- are apparently attracted to some degree to a woman (Harley Quinn and Machi).
- are endowed with a genius intellect that makes them unpredictable as well as fearsome strategists.
- are entirely amoral and focused only on their own interests.
- fight with playing cards and capable of killing using seemingly useless objects/abilities (the Joker's paraphernalia and Hisoka's Hatsu).
- seem to feel neither pain nor fear.
- are devoid of any regard for human life.
- have a mysterious past.