It goes quite well!

Shortly after Master called Rosemary in, the door opened, and the newest addition to our little family stepped into the bedchambers, looking puzzled, but excited. Rosemary swallowed dryly, before looking at me and Master as Master idly played with my nipples. "Erm, did you call for me, Master? I hope I'm not so forward as to be intruding on the Lady of the Night's night with you..."

I giggled, and replied, "Not to worry Rosemary... It was at my request that he call for you... Come, take your top off and join us..." I pressed my boobs into Master's hands.

Rosemary blinked, before smiling, and quickly shedding her top. As she approached, I got off of Master's lap, and settled for sitting next to him, nuzzling his side as he used one hand to grope me, and the other to grope Rosemary as she sat next to him on the other side. "Okay, so what's this about?" she asked me and Master.

"Well, our dear Lady of the Night suggested we start including the option of threesomes," our Master told Rosemary. "In the future, the Lady of the Night will be able to select another girl to join her and I during the night. This won't give you additional privileges like Celeste until the next Lady is picked, you're merely invited to join us."

"Oh," Rosemary moaned as he continued to grope her, and I grinned.

"I trust you won't say no?" I asked Rosemary, who smiled and shook her head.

"Of course not, my Lady! I'm always happy to serve you and Master!" she informed us.

I gave Master a grin and kissed his cheek. Rosemary had initially worried me, but she had succumbed to the joys of being Master's ****, just as I had. And I would certainly make it my mission to ensure she never regretted it. I moaned as he pinched one of my nipples, Rosemary doing the same as she got the same treatment.