Belly pet

You move over to the bulge the floor of the stomach reacting to your movements "I can never show my face to the outside world again. The shame and humiliation of being a dragon's pet or ****. However, I would very much like to live. If you say you can use magic to keep me alive in here then I would very much like to stay, it is warm and comfy and you seem nice to talk to. " You conclude.

"VERY WELL, YOU WILL NOT LIVE FOREVER BUT FOR THE REST OF YOUR LIFE WHATEVER ENTERS MY STOMACH IS YOURS TO DO WITH WHATEVER YOU LIKE." Stardust replies.

You see a bright light emanate from all around you. It moves towards your body and your body changes. You can see better in the near darkness seeing the full extent of the stomach. Unknown to you, your body inside and out changes to become immune to acid and enzymes and you no longer need to breathe. Your stomach changes to be able to handle tough raw meat. The most drastic change happens last. You feel the skin below your testicles rip open. No blood runs instead you feel a cavity from and the skin becomes sensitive. You feel down and guess (due to lack of experience) that you have grown a vagina. You still look like a man with a flat muscley chest with hair on it instead of breasts but apparently, Stardust thought you needed both parts to fully enjoy both genders of knights that she sends down to you.