The mantle of stars spread as the Princess of the Night descended into the royal balcony.

“Rest my sister, as always I´ll gu-”

“SURPRISE!!!!”

Princess Luna reacted like trained, creating a dozen magic weapons and placing them at the throats of her assailants. Pinkie was the only one who made a soft “pfft” sound with her blowout.

“Luna, please put the weapons down...” Celestia calmly said.

“What is the meaning of this?” Luna demanded to know.

“Is your birthday, silly filly!” and she playfully poked her nose.

Luna took a good look at all the ponies with hats and party accessories and the giant banner that read “Happy 100th Birthday, Luna!”

“Is this your idea of a mockery, sister?”

“No...” and Celestia levitated a present. Hesitantly, Luna opened it and was met with a shower of stream and confetti. “That is!”

Everypony laughed along with the Sun Princess but Luna just growled in anger and teleported herself out of the room.

“...guess she doesn't´ like surprises.” Applejack said.

****

Celestia found her sister in the observator, looking at the full moon with almost tears.

“That was pretty rude of you, Luna.”

“Why, sister? Why did you did that?”

“I told you already, it´s your birthday so I invited some friends to celebrate it.”

“But the flag read a hundredth! I spent over a millennia on the moon! What was the purpos-” but Celestia placed a hoof on her sister shoulder to maker her quiet.

“The MAre in the Moon wasn´t you Luna. This is your first birthday since you came back. On the last one you were about to turna hundred, remember that?”

“Yes and nopony at all showed up. They all went to hide at their houses!” for a second, Celestia was able to see the silhouette of Nightmare Moon but the moment was gone and her small sister was back.

“And now see how many ponies are here for you, how many friends you have now. Please, let this be your chance to start things over, our chance...” and Luna turned over to see that her sister was also on the verge of tears.

“Very well, sister. Let us join the celebrations.”

“I´ll take that as a Thank you for the party, Tia!”

And the two sisters went back inside to blew a cake with exactly a hundred candles.