Supposing that Hisoka's intentions could be simplified as prominently self-centered and moved by his own greed and lust for battle, Illumi's could be considered far less self-aware comparatively. Having thrived twenty four years in a world of general estrangement from human society, it was safe to assume that the magician was in all likelihood the only individual with whom the eldest Zoldyck sibling actively involved himself with (outside of the blood of his kin or contracted clients).
The elements of their relationship were far less cut and dry to one who did not ever seek any iteration of intimacy through conversation or even the simple company of the presence of another. Of course this was at once quite as unconscious as it was entirely conscious to Illumi, who had been wired since birth to avoid pursuing the interest of fulfillment through friendly affection. Naturally this set the stage for an essentially linear road on which to relate to his existence, safely disconnected from the potential distraction of something as trivial and unnecessary as human acquaintanceship.
Yet somehow or other, the meticulous programming of his elders did not serve to effectively isolate him, as of course he had ultimately found some sort of convenience in Hisoka. He could not reasonably identify what precisely this convenience was rooted in, but indeed it existed as clearly as the multitude of concepts to have inheritably befallen him in the past which he had never questioned too deeply either.
The advantage to this uncertain "convenience" revealed itself during a time in which his personal goals actually opposed that of his family. Without the willing aid of his kin to assist him, there was fortunate value to be established through his questionable connection to Hisoka. After all, there was honestly no one else he had so much as spoken to beyond the reach of the Zoldyck estate that did not otherwise simply remain within the limits of employment, which hardly counted whatsoever.
Inwardly, and either subconsciously or almost fully unconsciously, there was a strange and obscure contentedness to this arrangement. His mortal coil, which remained purposely locked behind the same wall that maintained distance between his ambitions and his forbidden self, could not in fact deny the animal need to be associated with entities other than simply his own psyche. If ever he had truly felt the pangs of devastation in his own solitude, the effects were long forgotten and dismissed by his notably responsive self. Rather to say that the more profound, latent region of his instinctual reflexes sought the rationally prohibited reward of sociable company.
This was however, not to be mistaken for "trust"; whether by definition or simply by concept. On the contrary, there was a sort of phantom reaching for physical imminence in terms of proximity (speaking in terms entirely isolate of sexuality). There was already too strong of an association with the follies of vulnerability for even the most inaccessible portions of himself to properly crave. No, Hisoka was a convenience merely because there had never been any other before him. Most probably, there would be no other after, either…
Instead it was perhaps secretly and rebelliously gratifying enough to quietly and subliminally defy his own sense of self without particularly understanding that he was actually defying his sense of self at all.
A/N: So, this officially ends the twoshot analysis. As a side note, thank you to "HunterXZain" for your reviews of both this story and "Nurturing Control" (I tried to PM you to express this, but you have PM turned off). :P
...And of course thank you to anyone else who has read this or reviewed XD