Illumi Zoldyck was a man who didn't belong in any category but his own, who took the labels that society put on people, melted them in acid, and reshaped them until he held in his hands something that he approved of.
He was the eldest of all the children in his household, and as such, was groomed to be the perfect, spotless model for all the following children born. Both the mentor and the role model responsible for his younger siblings, he was almost the third parent of his family, if not more because of the sheer limitless measures to which he would go for their sakes.
There were no passions that Illumi had to speak of, but his muse was his beloved little brother, Killua, whom he loved to the point of possessiveness. Hisoka wouldn't be surprised if Illumi had been the one to give his little brother his own name.
He was the quiet type, another predator of a different kind, who observed carefully and snatched his victims out right in front of their families' eyes before they even realized that their own homes had betrayed them. He was the shadow that nobody noticed, the creeping disease that took everyone by surprise because they hadn't known it was deadly.
He, like Hisoka, was also of the androgynous sort, but merely in appearances rather than any mannerisms of his own.
His face had the sort of beauty that marble statues and their sculptors hoped to achieve. Silent and serene, sophisticated yet soft bone structure and lips like finely carved ice. Pale skin that, in accordance with his Zoldyck genes, never tanned or burned. Hair black as midnight, that flowed away from his face and draped on his shoulders and over his back like a thick ebony curtain. But it was his eyes, in Hisoka's opinion, that were the most memorable of all his features, those so very large, shapely eyes that were so dark they greedily sucked the light right out of the very atmosphere and gave none of it back.
Illumi had a way of making you feel very small and very weak with just an offhand glance. He was soft-spoken and rarely, if ever, raised his voice, every single emotion shuttered out and locked up tightly behind that smooth visage until they no longer seemed to exist. Instead, he knew of bloodlust and ruthlessness, of taking what he wanted and changing what he didn't like.
There was a rare kind of beauty inside of Illumi Zoldyck, in the sense that new computers and well-oiled machines were like, and he was Hisoka's until that beauty wore itself out.