Pinkie pie trotted into the room, her usual pink cloud of hair lay hanging like a deflated balloon.
"No.... no! This can't be happening!" She yelled miserably, already starting to crumble. She started crying loudly, with The dying princesses laying in wait for her temper tantrum to settle...
"Pinkie... we don't have long... you must listen..." groaned Luna.
Pinkie settled and sat down. Her usual smile lost long ago.
"You brought us... many happy memories... and made our lives feel like one big party," chuckled Celestia weakly "but where we are going, and one day where you will be going, you will have as much time to party as any pony could wish for."
" So... i'm going to see you again? You're only moving castle?" Pinkie pie asked, a spark growing in her eyes.
Celestia and Luna looked to each other and inwardly agreed on the statement.
Celestia put her hoof under pinkie's jaw and made her look up up into her eyes, as a mother would do to a child.
"Yes, my little pony. You will see us again. And we shall have many parties with the other pones who have moved there."
"You mean like...gummy? Big Mac? Granny Smith? My parents?"
Celestia nodded.
Pinkie pie, for the first time in five years, smiled, her hair bursting with confetti that nopony thought would be seen again.
"Thank you so much princess! I am so happy now! Omigosh omigosh omigosh!"
Luna now turned her head to pinkie. " we have to leave soon. May we talk to the others?"
"Oh yeah! Sure! See you soon princesses! " hopping away, pinkie giggled at the prospect of a mega reunion party.
"We will, element of laughter..." chuckled Luna lightly.

Author's Note

I liked the prospect of a mother and child kind of setting inbetween the princesses and pinkie, almost sort of using it to maintain a level of innocence to pinkie's character.