Pinkie Pie trotted past the guards with the usual spring in her step as she approached the throne of Princess Celestia herself. The Princess sat upon her throne, her poise regal as ever, her eyes closed and smile serene as she enjoyed the rare, beautiful moments of peace and and quiet that came from a Solar Court that was actually empty of bureaucrats and nobility, at least for the moment.
She opened her eyes to the sound of Pinkie's hoofsteps, her smile widening to a grin. Pinkie bounced in, stopping momentarily to bow, as was proper etiquette.
"Hello, Pinkie Pie!" Celestia said, "Always a pleasure! I assume you're here to bolster your supply?”
“You betcha!” Pinkie replied, her voice as cheerful as ever.
With a nod, Celestia walked out of the throne room, Pinkie skipping after her. Eventually, the two of them came to a store room, where Celestia magically opened a door lock to reveal several canisters of helium. The helium had been procured by Celestia herself, one of the lesser known perks of being a Princess of the Sun.
Pinkie grinned an impossible grin. “Thanks a super duper lot, Princess!” Pinkie said in gratitude, before reaching into her hair and pulling out a cake-sized box. “Here you go, one Quintuple Choco Brownie Cookie Cream Cake!” She leaned in closer, adding in a conspiratory manner, “With my special Mint Marzipan frosting!”
Celestia beamed, taking the cake in her magic. “Thank you, Pinkie, I always enjoy your cakes!”
**************
Later that night, in her dreams, Pinkie Pie received a visitation from none other than Princess Luna.
“Wow, two Princesses in one day?” Pinkie said excitedly.
Luna smiled. “Good evening, Miss Pie. I managed to get a taste of a cake that you baked for my sister, one of several delicious and unique confections you trade to her on a regular basis in exchange for a certain lighter-than-air gas...”
“That’s right!” Pinkie said.
“I should like to make a similar deal, if I may?”
“I’d love to, your majesty!” Pinkie said excitedly, before deflating a bit, “Oh, but, ummm...I already get all the helium I need from Princess Celestia.”
“Indeed.” Luna confirmed with a nod, “I offer something different from my domain, though…” She leaned in closer to Pinkie, and asked, “Have you ever heard of helium three?”