Chrollo is of phantom troupe and y/n is from the scarlet eye clan. Yes chrollo had killed/ taken eye out of the members of that clan but obliviously left two people y/n and kurapika. But here’s the catch y/n’s eye is mix of scarlet and navy eye (both are rare clan which are already dead) making her eyes faint purple. Only in the book they had ever heard of eyes pretty as that.