Angels We Have Heard on High Tell Us to Go Out and Buy
One would have to be both blind and deaf not to notice Hearth’s Warming’s approach in Canterlot. The sights were largely the same as the rest of Equestria: snow, wreaths, pine trees, and so forth. But in addition to foals cheering and ambush parties of carolers assaulting unsuspecting ponies with festive cheer, there was another bit of seasonal sound unique to the capital. As the end of the year neared, the eternal whispered gossip of the nobility revolved around the question of which Hearth’s Warming party Princess Celestia would attend.
The Princess was always coy with her consideration, always careful not to show undue favor to this courtier or that. The nobles approved of this. After all, even if they were snubbed from time to time, at least everypony else was as well.
So it was that after the Fall Finale, as the first shipments of snow came trundling out of Cloudsdale, preparations began for the biggest collective social event of the year. While the Grand Galloping Gala was the premiere single soiree, the combined efforts of the noble houses to attract the princess come Hearth's Warming outweighed it in ostentation and expense. Especially expense. Centuries of gradual escalation had made the cost of a true Canterlot Hearth's Warming party ruinous to all but the wealthiest houses, and even they found it prudent to wait a few years before hosting another.
Because of this, House Sanguinius was the favorite to claim Celestia's presence. Canterlot was abuzz with Prince Blueblood XXXVI's choice to host another party only two years after his last, and even bigger than that one, the better to incorporate his son and heir's cuteceañera.
Of course, that didn't mean that the other nobles were going to lie down and admit defeat. Canapes were purchased by the cartload, tinsel by the mile, Chevaigne by the gallon (Actual Chevaigne, imported from the appropriate region of Prance, as if it needed to be said.) No fewer than seven of Equestria's oldest and most illustrious noble houses threw millions of bits into their parties in the hopes that the consumption would be conspicuous enough to draw Celestia's notice.
And then came the moment repeated so often that it had become tradition. On the evening of Hearth's Warming Eve, as the bells of Celestia's School for Gifted Unicorns struck seven understated notes that still managed to carry through the whole city, every noblepony in every ballroom raised a glass of Chevaigne in hoof, wing, or aura and looked to the main entrance, waiting to see if their efforts would be rewarded.
Celestia considered her destination. The house could not be considered humble. Humble simply wasn't an option in Canterlot real estate, and it certainly couldn't apply to a building with an observatory dome sticking out of the roof like a camel's hump. Still, compared to where she was expected to be tonight, it might as well have been a thatched-roof cottage. She smiled and knocked on the door.
Her eyes widened at the ensuing ruckus on the other side of the door, full of shouts, crashes, and the staccato clopping of little hooves. A few moments later, fuschia magic worked the latch, and the door opened to reveal a wide-eyed filly. Her smile nearly split her face in two as she lunged for Celestia and cried, "You made it!"
The princess smiled as she returned the embrace, a bit of her amusement from the tension of the covert guards scattered across the street and the shadows. "Of course, Twilight," she said.
"Come in! Come in!" Twilight Sparkle halted in her tracks, then turned to face Celestia with an expression of utmost seriousness. "Wipe your hooves first, or Mom will be mad."
"Well, we wouldn't want that." Celestia dutifully wiped her hipposandals on the doormat, taking in the house. Her main impression was one of bookshelves. There was at least one in every room she could see from the entry hall. Plenty of seasonal decorations and other decor, but the house seemed to be as much library as home. Of course, that was how the family liked it.
Twilight nodded once she was satisfied with Celestia's preparations. "I'll go get Smarty Pants." She trotted up the stairs, passing a colt well on his way to stallionhood as he stumbled down them.
"Twilight, get back here!" he cried. "Spike's trying to eat my ear again!" Still looking at the filly, he lurched muzzle first into Celestia's side, only then turning to see what he'd hit. "Sorry, Pri—" Both eyes bugged out as his jaw dropped, sentence forgotten along with the dragon hatchling still savagely gumming his ear.
Celestia smiled down upon him. "I take it you are Shining Armor?"
He nodded dumbly, still slack-jawed.
She nudged his mouth shut with a hoof, then tickled Spike under his chin with a wing until he fell giggling off of his quarry and into her magical grip. "Your sister has told me a lot about you, Shining Armor." Celestia's smile widened a bit. "As has my niece."
Shining's pupils shrank to pinpricks. "Oh," he croaked.
Celestia leaned close and whispered, "Carnations are her favorites." She pulled back and gave him a wink.
"Celestia!" Twilight Velvet walked in from the kitchen, smiling and stirring a bowl of something in her magic.
Shining squeaked like a dying rodent. "Mom?"
Velvet laughed.. "Relax, Shiny. Once you've been turned into a houseplant in front of somepony, you feel much more comfortable around her."
"I wouldn't know," Celestia said with a smile. "Still, it's good to see you again, Velvet."
Velvet nodded and watched Shining take Spike from Celestia and go back upstairs, alternating between giving his mother a horrified look and gazing at the princess in awe. Velvet sighed. "Well, he's at the age where he'll be ashamed of me no matter what I do. I might as well earn it." She turned back to the kitchen.
Celestia followed her. Even the kitchen had a shelf for cookbooks, though given how none of them were open, Velvet seemed to be making her current recipe from memory. "So," she said as she dolloped cookie batter out of the bowl and onto a baking sheet, "about this apartment on the castle grounds where you want Twilight to live."
"Not for several years, Velvet." Celestia sighed. "If I'm right, we'll all be asking a lot of your daughter in the future. I'm not going to take her foalhood away from her."
Velvet glared at her. "We're going to need to talk about these plans and premonitions of yours. As you just said, this is my daughter we're talking about. At the very least, I want to know what you think she's going to deal with."
“I’ve tried telling my student everything ahead of time.” Celestia shook her head, trying to chase away memories that still felt fresh months after the portal closed. ”It didn’t end well.”
“Lying to your children for their own good is a big part of parenting.” Velvet looked at nowhere in particular. ”Besides, ever since Twilight’s first surge became an article in the Canterlot Journal of Radiology, I’ve known she was going to either save the world or destroy it.” She turned back to Celestia. ”I’ll take anything you can tell me that will make sure it’s the former.”
"I will, Velvet, and soon, but right now I'm intruding enough as it is." Celestia gestured towards the holly bunches on each corner of the bookcase. "This is Hearth's Warming Eve. It should be a time for togetherness, not listening to an old nag's worries."
Velvet chuckled. "You've clearly never spent Hearth's Warming with my Grandma Twinkle." She floated the baking sheet into the oven.
Celestia looked around. "Where is Night Light? I haven't seen a trace of him since I came in."
"We're expecting a visit from the spirit of Puddinghead later. He's putting together the spells that will let him think inside the chimney without leaving soot on the carpet."
"What do you mean?"
Both mares jumped and turned to see Twilight Sparkle looking up at them, a little frown on her muzzle and a stuffed toy on her back. "Why would Daddy need to help the spirit of Puddinghead?"
"To keep the house clean, sweetie," said Velvet, giving Celestia a split-second smirk. "Chancellor Puddinghead never had to clean up after himself. That was Smart Cookie's job."
"Oh." Sparkle frowned a bit longer. "I suppose that makes sense." She turned to Celestia and beamed. "I can't believe you really came!"
Celestia returned the smile. "Twilight, I've only just arrived, and I can honestly say that this is the best Hearth's Warming party I've had in centuries."
Author's Note
I've seen the idea of Santa Hooves the jolly reindeer bandied about a lot, but Hearth's Warming isn't quite Christmas, and transposing the mascot of one onto the other feels a little off. Especially when there's an equally jolly figure with a similar affinity for chimneys already available.
And yes, I'm fully aware of the irony of that thought process given the story image and the origin of the chapter title. 
