The bigger the bounty, the more dangerous the fugitive.
Khan, a Chamele warlord, has a huge bounty on his head. His enemy is willing to pay an outrageous amount to secure him. Khan wants to be apprehended, especially if the bounty hunter is a particular brown-eyed female with razor-sharp daggers and an even sharper tongue. He'll allow her to subdue him sexually, his passion and prowess not inhibited by restraints, and when she collects her bounty, he'll collect his revenge, killing his enemy and claiming his little bounty hunter forever.
Zeta doesn't do forever. She captures the worst scum in the galaxy and trades them for credits. Khan is fierce and sexy and the most dominant male she's ever encountered, but he's also a fugitive. Once she sates herself with his body, she'll betray him. That's her job.