Zoldyck family assassins aren’t supposed to have friends or any other relationships outside of family. Illumi has always stood by and enforced that rule. Attachments are a weakness, and weakness gets you killed. Sure, he uses Hisoka in some of his operations, but that’s strictly business. They both benefit in one way or another in the end and there are no emotional ties.

So why does he find himself drawn to that clown’s younger sister? He doesn’t even know you that well, or at all really. You just happen to be around more often now, standing in Hisoka’s shadow. He’s only ever heard you speak a handful of times, usually to Hisoka. He isn’t even sure if you can fight. He does sense nen aura from you, but it seems either weak or suppressed.