His Sub's Submissive (Club Esoteria #1)

Erotic romance author and closet submissive Sloan Newman wondered what being a sexual submissive would be like. When her cousins Jenna Best and Taurus Green offer her a chance to take part in the slave auction their BDSM club is holding for charity, Sloan agrees. If nothing else, she'll be able to use the knowledge gained in her future writings. It's Master Dane Bennett's life partner/sub Merlin Gates's 30th birthday and Dane wants to buy him a gift - a submissive little pet they can both play for the weekend. As soon as the bisexual men see Sloan on stage, they know this is the woman they've been looking for. After spending the weekend introducing her to BDSM, they realize she is the woman they want to complete their family. Now all they have to do is get her to agree to be His Sub's Submissive.

Note: The main character is a pediatrician.