It was Hearthswarming Eve, and Diamond Tiara had been kissed goodnight by her parents and carefully hung up her stocking of fine purple velvet for Santa Hooves to fill with good things, but she had other things to do then spend the night sleeping with visions of sugar plums dancing in her head. She sat up and read a book for a while about the history of Equestria and then crept out of her bedroom and down the grand staircase of the Rich Mansion, past her parents bedroom , past the sleeping servants, past the grandly oversized Hearthswarming tree on the ground floor with it's huge pile of presents, and down to the cellar with it's barrels of wine and hard cider.
Walking behind the tallest of them she pressed with her hooves on a panel which opened up like a cat-flap and entered a dark twisty tunnel, lit only by areas of glowing green webbing. After walking for a while a pair of blue eyes lit up the area in front of her, and the owner of the eyes let out a hiss. "Who goes there?"
"Like, Phalanx, it's only me. The First Daughter of the Hive. Here to see my mother on the Long Night, which those ponies call Hearthswarming." And with a blast of green fire, Diamond Tiara took her true shape as a miniture version of a Changeling Queen, clad in black chitin and with the same cat's eye pupils as Queen Chrysalis. The two soon entered the Grand Chamber of their hidden Hive, where hundreds of changelings awaited them.
"The First Daughter is here! It is time! Light the candles and let the darkness flee away!" A score of wax candles were quickly lit, filling the chamber with the glow of candlelight. Diamond Tiara trotted up to Queen Chrysalis and let her forehead just below her horn be kissed, loving-in so much as a changeling could love anyone or anything-being with her true mother.
"The Long Night begins," said the Queen. "Bring forward the presents and let everyling be merry." A huge pile of presents was brought forward, and every changeling had at least two, one from the Queen and one from one of their friends. There were fine black leather saddlebags, books of all kinds, necklaces of opal or other jewels, elegant knives forged by changelings, nice clothes for wearing when undercover, and many other things. Diamond Tiara's share of the spoils of the Long Night was a set of fine black leather saddlebags, a fine necklace of gold set with amethysts, a book about pony history, a book about changeling history with a false title to hide it's true nature from ponies, both of them bound in black leather, and a tiara set with black pearls, as well as another kiss and a cuddle from her true mother.
Diamond Tiara considered herself very lucky to be the First Daughter, the first of the Queen's first clutch of changeling eggs to hatch, the first to use her horn to crack her eggshell. As such, she was the heir to the throne of the Chrysalis Hive and got a lot more love and affection, more access to the Queen when not undercover, and was taught the dark arts of how to properly rule a Changeling Hive.
When the last present was opened, cocoons were brought out containing ponies, griffins, buffalo, and many more races of Equestria, most of which were only fed from by most non-royal changelings upon the Long Night. Of course, rather then eating their meat, it was their love they feasted on. Pony love was perhaps the sweetest. Griffin love tended to be spicy and hot and not all changelings liked it and griffins were very hard to bring down, as their fearsome claws and beaks could rip and tear through changeling chitin. Buffalo and minotaur love was chewy, and took a while to digest. Each different love had a unique taste. Changeling love was very much not on the menu, as that was seen as cannibalism.
There was lots of pony food here too, apples and grapes and mangos and nuts and cakes and rolls and Hearthswarming puddings-plenty of food for hungry changelings to get their fangs and other teeth into. Many changelings looked forward to the Long Night for most of the year, as even when things were going wrong for the Hives, their Queens always tried to make the Long Night something that would be great fun and well worth the wait.
When the feasting was done and the changelings had bulging bellies and fully stuffed love sacs, Diamond Tiara said to the Queen "Thank you, Mother, you have spoiled us all tonight in a good way. I wish I could stay with you and the rest of the Hive."
"There is not enough food most of the time, to provide all this love for the Long Night we have gone hungry and on short rations for the last month. That and you need to study pony society and have an independent love source to feed upon. It is time for you to go back and enjoy the pony Hearths Warming Day. We can meet again on your Hatching Day. One day we changelings will rule over the ponies and then you can stay in the Hive all the time."
Reluctantly Diamond Tiara let her real mother kiss her cheeks, put her presents in her saddlebags, put her saddlebags on with her changeling magic and took her purple earth pony shape. Then she trotted up out of the hidden Changeling Hive, back into the Rich mansion and back to the comfort of her luxury bed, noting that there was a stuffed stocking full of good pony things hooked up to the bedpost. Clearly Santa Hooves had been and gone, and it was time to snuggle up, get warm and fall asleep with many happy thoughts of her real mother in her mind, and of the Hearths Warming celebrations to come.