Celestia gave a soft groan as she fought against her body’s urgent needs.
“Lulu, I’m sorry! Please let me in, dear sister! I’m about to soil my favorite panties!” Celestia’s voice resonated with a tremble as she worked to compose herself.
“We are sorry, sister, but we cannot allow you to come in.”
Celestia sniffled some as tears welled up. Her body won over her ancient will as she began to hastily fill up her Luna printed panties.
“L-Lulu? It happened… I… I’m so sorry…” Celestia’s voice became soft, much like that of an embarrassed child.
Luna smiled softly from behind the bathroom door. “We know you are, sister. Now you know what it was like for us on the Moon.”
The moon princess paused to shake a bit, her own rump being clasped in clothing and filled. “Let us get you changed and have some ice cream.”
Celestia, resigned to her fate, rested against the royal bathroom door. “O-Okay Lulu…”
Luna’s method of bringing her elderly sister into a more submissive mare had finally worked. The Sun goddess was broken, and was now at the mercy of the Moon mare. She had more planned for Celestia to learn what being vulnerable truly felt like, but for now it was one step at a time.