Spike stared around him, jaw dropped and eyes wide. An expression that had been on his face for a while now, after the events at Fluttershy's cottage, though now it was directed at a very different pink-maned mare. Sugercube Corner was a pony-powered pandemonium, from the streamers draped from the beams above to the balloons strewed liberally and nigh-literally everywhere. Barely audible over the sound of "Pinkie's Perfect Party Playlist" coming from the gramophone were the strained sounds of the Cakes doing business with the morning rush, accompanied by the pounding of hooves as the Mistress of Ceremonies herself tried to teach Gummy to tango. Taking a deep breath, the thoroughly flummoxed dragon whelp made one last bid to make himself heard over the ruckus.

"PINKIE!" he shouted, accidentally releasing a small stream of green fire as he did, which left no trace of a plate of yellow cakes which had been in front of him. Instantly, the music stopped, and in a magenta flash, said earth pony was snout-to-snout with him, her usual wide-eyed smile stretching wildly across her face. Spike yelped and fell backwards, little arms wind-milling frantically.

"Yeees Spike?" Pinkie trawled, accompanied by twin sighs of relief as the bakery resumed business at a more reasonable decibel level. "Oh, you silly billy, don't tell me your Great-Aunt Pinkie scared you?" she finished with a giggle. Spike stared up at her blankly.

"Great aunt? What?" he asked, bemused.

"Of course! As the eldest, naturally the rest of the gang look up to me as a cool aunt figure, and since Twilight hatched you from an egg, she'd be your mother of course, making me your great aunt!" tutored Pinkie enthusiastically. Spike rubbed his eyes, which had gone rather dry from all the blank stares he'd thrown since coming through the door on a quest for brunch, and decided to make a brave stand for logic. Somewhere, a lavender unicorn felt suddenly proud.

"Um, Pinkie? Fluttershy and Twilight are a year older then you." he pointed out, being careful not to blurt out that a certain alabaster fashionista was three years older then Pinkie Pie. He had Pinkie Pie-promised, after all.

"They are?" gasped Pinkie. "Why, they never said! I wonder why.." A frown crossed her face , coincidentally matching the expression of a certain ex-supermodel. A moment later, she brightened as a thought struck her. "Wow, I feel suddenly younger all of a sudden! I guess I'm just your regular ol' aunt huh, Spike?" The purple whelp shook his head.

"I dunno, Pinkie. Sure, Twi hatched me and all, but Celestia was the one who looked after me when I was little." A little giggle escaped his erstwhile hostess, and he sighed. "Fine, littler. But yeah, me and Twilight've never really had much of a mother-son thing going on. She's more like..." he paused, scratching his scaly chin thoughtfully. "like my big sister. My annoying, nerdy big sister." he said, smiling. "We drive each other up the wall a lot, but we're always there for each other when it counts! That's siblings, right?" Pinkie nodded vigorously.

"That's how my sisters back on the farm always described it! Though I never understood where the wall-driving part came from..." she said wonderingly. "Still, Rarity and Sweetie Belle are always falling out and in and up, so I guess it's true. And if you don't want to be all genetic about things, Applejack and Dashie are..." Stopping abruptly, Pinkie Pie suddenly let out such an ear-splitting gasp that Mr Cake dropped a plate of cupcakes on a customer whilst Mrs Cake almost went into labour right there and then. "Oh! If Twilight's your non-biological sister, and I'm Twilight's non-biological sister too, then that means... brother!" Spike was suddenly thrown to the floor, having the air squeezed out of him. "Oh Spike! I always always wanted a little brother, and now I have one, and I'm so glad it's you! You're so nice and sweet, and you say the funniest things!" Once again, Spike found himself being mercilessly nuzzled in public. Not that he honestly minded the mushy stuff, but he did have an image to maintain as the manliest dragon in town.

"Geez Pinkie, cut it out. You're embarr-" Spike cut off mid-gruff, words struck from his mouth by the sight of tears in the corner of her eyes. Feeling a stinging in his own, he did his best put-upon sigh and returned the nuzzle, arms tight around her neck. "Yeah yeah, I love you too, Pinkie... sis." he said in a low mutter, trying to not be overheard by the patrons of the patisserie, or draw any more attention. A desire destined to be ignored, as the happy earth pony started bawling loudly and clenched him even tighter to herself.

"Should I even ask?" drawled a familiar voice, and Spike looked up to see his avowed other sister standing in the doorway, one eyebrow arched. A quick struggle to escape being caught by his library-mate in yet another sappy situation (mercifully a far cry from the type the Crusaders generally found themselves in) proved futile: the legs crushing him into the party pony's embrace might as well of been made of iron. Spike knew in a general kind of fashion Earth ponies had a robust physique, but damn. Even when she removed one leg, he was clamped down like a cart that had dared to park in Mayor Mare's space, though shock alone would of rendered him immobile as the other leg stretched across the distance and hooked the startled unicorn around the neck. Twilight had only enough time for a surprised whinny before she was dragged across the room and into the loving huddle, jabbing her number one assistant in the spine with her horn something vicious in the process.

Groaning, Spike rubbed himself with his tail and focused his eyes on the faces of the two ponies. Pinkie Pie's eyes were closed, and though her grin was as wide as ever, her happy expression seemed subtly different somehow. Less... reserved? Guarded? Spike couldn't quite put a claw on it, but her mane seemed pouffier then usual. Twilight's face on the other hoof was staring at Pinkie's with a long-suffering expression on her face, though the corners of her mouth were twitching upward slightly. Evidently feeling Spike's eyes on her, the two Canterlot natives shared a look of loving exasperation for a long moment, before Twilight's curiosity finally couldn't be restrained any longer. "Ok, I'll bite. Is this in aid of anything special, or -"

"Yup!" interrupted Pinkie Pie, her baby blues staring into Twilight's purples at so little a distance that Spike was uncomfortably reminded of certain magazines he, Snips and Snails furtively poured over. "It's the most super-duper special thing ever! Me and Spike -"

"Spike and I." corrected the lavender unicorn.

"- just worked out we're related! Isn't that simply the best!"

"What." dead-panned her captive audience.

"And we'll tell each other secrets – though I already know about Rarity" Pinkie Pie continued, dropping her voice to a stage whisper, which was luckily drowned out by the cacophony coming from the grammar-phone, "and talk about colts and mares, and do each other's manes – or spines I guess... Oooo – will you be roughing up my prospective suitors? Giving them the third degree?" she finished, seeming delighted at the prospect.

"Of course!" Spike growled. No pony better think about messing with his ponies, he thought heatedly. Pinkie Pie grinned rather toothily at this, and immediately started rambling about her dashing love interests fighting the little dragon for her hoof in marriage. Twillight, on the other hoof, looked distressed.

"Wait, so does that mean you think we're all... related or something?" asked Twilight, that Spike's finely tuned senses could only describe as "kinda weird", which would also have been an accurate summary of the distressed grimace that had spread across her features. Spike couldn't make head or tails of whatever it was the lavender pony was feeling, but evidently Pinkie Pie could, and judging by her expression she didn't like it one bit.

Mane seeming to straighten by itself, the watery-eyed Earth pony shoved her face right into Twilight's, her right ear furiously oscillating. "You... don't want to be sisters, Twi?" she began, her hesitant voice too different from her usual joyful jabbering for Spike to handle. Ignoring how the little dragon had begun to sob quietly, Twilight's eyes determinedly avoiding Pinkie Pie's. "Why, Twilight?" the latter continued, utterly heart-broken. "I thought we... were... oh."

Spike peered out between the claws he'd covered his eyes with. "Oh?" he echoed, hoping that somehow everything was ok. Twilight was looking even more awkward then usual, and Pinkie Pie looked... thoughtful.

"Oh. Ohhhhhhh." Pinkie Pie rubbed her chin thoughtfully, without releasing either companion. Her eyes, suddenly clear of any sign of tears, flicked back and forth between her captive unicorn and her spinning ear, looking uncannily like a certain mail-mare. "So that's what that sign means."

"Oh Celestia..." sighed Twilight. Was she blushing? Spike was now totally confused, but if the two ponies were friends again, whatever. His musings on the madness of mares were interrupted by a flash of light, and he fell forward into a pile with Pinkie Pie. Looking up blearily, he took in the sight if Twilight's head sticking through the shop window.

"'slateforasuitfittingatRarity'sandwe'dbestbegoingsobye!" Horn lit up, Spike felt himself slammed onto Twilight's rear end at a force that made him glad she wasn't the overly athletic type, and before his ears could stop ringing, the manic unicorn was galloping off.

"Bye guys! I'll speak to you later, Twi!" yelled Pinkie Pie from the window, waving happily. Twilight just ran faster.