PHBBBBT was all Cindy heard. It made her laugh and moan with relief.

The last of your sanity left with the waste coming out of your mouth. Your brief hiccup in consciousness was strange to you, as it had all felt so alien. Nevertheless, you ignored the oddity and continued to serve your Goddess with full focus. The pressure inside of her still needed to lower, and you were still enjoying the sweet taste and smell of the bowl below. You looked down and could barely see any of the white lining of the side, and the water that was left was brown and opaque. It was beautiful.

"Oh my God, Tim!" Cindy yelled as nature finished running its course. "That had to have been my biggest shit in years, but I feel soooo much better now! You still hanging in there?"

pfft

"Hahaha you still got your sense of humor even after all that. I guess I know you're very serious about your new job! I'm lucky to have someone so nice as my butt-buddy!"

pfft pfft

"I don't know if we'll ever find your body, but I guess if we don't you can consider yourself lucky too to live in an ass as perfect as mine," Cindy again laughed to herself. In her mind, she was no longer seeing you as a human, but instead as her living asshole. Her massive dump had been like an accidental test to see if you were actually serious about staying as her asshole, and as far as Cindy knew, you passed. The transformation was complete; you were Cindy's permanent poopchute.

Days and weeks and months passed. Cindy continued her life as normal and still remained friends with your old roommates, who eventually also gave up looking for your body. At first they'd try to talk to you, but whenever Cindy would spread her cheeks for them all you'd do was let out gas. Your look changed to completely match Cindy's old asshole, with a few short blond hairs surrounding your form. Eventually they all stopped checking in on you as they were getting tired of your smell, and were indistinguishable from any other woman's asshole. Cindy even tried on the pair of panties that had the rest of your body, but when you saw it you couldn't recognize it as anything important. It was lost when they were put into the washing machine again.

Despite the world moving on without you, you remained as eager as ever to serve your Goddess, and there was never a shortage of opportunities. You happily burped out all of her flatulence and remained in constant excitement whenever one of Cindy's classic dumps would force itself out of you. The taste and the smell were something you could never get enough of, and they helped keep you in a state of constant bliss. Cindy would still talk to you a little bit here and there, and when you recognized her speech you'd always respond by saying how much you loved the Goddess. But to her ears, it was never anything other than a small pfft.