Alluka Zoldyck

Alluka Zoldyck (アルカ, ゾルディック) is the second youngest sibling of Killua. He is said to be a dark, uncontrollable child with the ability to grant wishes. His eldest brother Illumi currently wants to kill him and his younger brother Kalluto has apparently been trying to bring him back, perhaps not physically, but mentally, to a normal state so that he is no longer imprisoned by his own family.

Appearance
As of chapter 322, there is considerable confusion as to Alluka's gender. While he is mentioned by Illumi and by the 2004 data book as a 'younger brother' and by the servants of the Zoldyck family as 'young master', Killua--the closest person to Alluka--refers to him as 'younger sister.' One possible theory to explain this is that he is male by birth and has dissociative identity disorder, and only Killua knows his female personality.

She/He has black eyes. In Killua's flashback of her/his (Killua's) childhood in chapter 322 and in the family photo of the Zoldyck children in chapter 229, Alluka had long, straight, unbound black hair and wore boy's clothing. However, at present she/he wears the traditional clothes of a Japanese shrine maiden (miko), boots and a headband with happy and sad faces on them; there are two small straight bunches of hair, each of which is fastened by 4 hair bands that have a smiling or sad face on them each, hung down on the sides of the front of his/her head.

Wish Granting
Alluka can grant one wish if you will listen his three requests. According to Killua, the degree of wish that Alluka can grant is probably infinite. However, the greater the wish to Alluka is, the greater the next three requests will become. The one that must bear the cost of the next three requests is not the one Alluka granted the wish to, it is the next person who must do it. And if that next person declines to fulfill Alluka's requests four times, the one who declined the requests and the one that person loves most will die.