Bonus image because thestargrazer and f3l1×4r90 wanted some more mushbutt princess.

_“Lulu!~ Celly needs in the potty room…” Celestia chimed as she scratched on the bathroom door. Her rump was covered by a diaper that looked to be one of Luna’s, both in design and size.

“No can do, sister. I’m not done yet.” Luna sighed from behind the door.

Celestia whined softly. “But Lulu, I—”

Celestia was cut off by her stomach cramping up. The Alicorn princess began flooding and filling her once clean diaper uncontrollably.

“Yes, you what?” Luna asked with her ears perked. She could easily hear her sister having her little “accident.“

“I’m totally filling your—my diaper…” Celestia sniffled some. Her ears folded down in shame.

“Oh, dear~” Luna chimed. She gave a soft grin.

Neither Celestia nor Luna wanted to admit to the other that they secretly enjoyed doing such activities, but Celestia couldn’t help her body’s response. She drew long, hot breaths, but tried to stifle them.

“Art thou okay out there, sister?” Luna asked.

“Y-Yes, well, kind of…”_