The bought sex partner is the Merfolk King

Vivian, the biological daughter sidelined by her family, spends $8,000 to buy Ronan, a bottom-tier experimental merman treated as a “stress-relief punching bag.” Unexpectedly, in this lowly relationship, she finds loyalty and warmth—something Caspian, the competition-grade merman she spent millions raising but who has always favored her adopted sister, has never given her.