Board Thread:Questions and Answers/@comment-26005711-20151226104253/@comment-116.214.104.235-20180322101015

You have to take note that as per the Zoldyck Family, they don't kill or fight someone if there is no profit to it.

So this is why Hisoka contacted Illumi to kill him. (Reason for them to fight)

I'll go Hisoka :)