The mail-pony arrived at the Cake's residence not knowing what to expect. Every time he opened the mailbox, out would come a spring-trapped pie, or a water balloon, or a blast of confetti. On the rare chance it was empty he'd turn around and step on an expertly placed whoopee cushion. He gulped. Sure it was all in good fun and it usually gave him a good laugh, but after last week's prank, in which Pinkie mistakenly left her pet alligator in the mailbox rather than a pie, he was hesitant to even approach it.

"You okay there, Mr. Mail-pony?"

He turned around to find Applejack, carrying a basket full of apples on her back.

"Afraid a' the mailbox, huh? Don't worry, I'm headin' into Sugarcube corner to deliver these here apples. I can take whatever you got in to 'em."

The mail-pony nodded thankfully and pulled a rather heavy looking envelope out of his bag. On it, written in elegant, gray font, was the name 'Pinkie Pie'. He tucked it into the side of Applejack's basket and continued on his route. Applejack ascended the light-purple steps and knocked on the door. It immediately flung open.

"Aw... No mail-pony today?" Pinkie whined, peering out the door to the mailbox.

"'Fraid not," Applejack responded. "But ya do have mail! And I got those apples ya wanted!"

"Thanks Applejack!" Pinkie replied enthusiastically. She lifted the basket off Applejack's back and looked through it, examining each apple with intense scrutiny.

"Perfect!" She declared. "Now I can bake that humongo-double-decker-apple-cake! It'll be perfect for the twins' birthday next week!"

"Let me know how that goes," Applejack said, turning to walk away. "I gotta finish ma chores back home, so I'll--"

"HAAUUUGH!?" Pinkie's dramatic inhale sounded from behind her. Applejack shot back around.

"What's the matter?" Applejack asked, running to her side. Pinkie had opened the letter and was now scanning through its contents.

"Dear Pinkie Pie," Pinkie read aloud. "Mom and Dad say we're leaving tomorrow to keep up with the rock migration, so we'll probably be down south for the next few months. Just wanted to give you a heads-up. Also, here's a rock. Love, Maud."

Pinkie turned the envelope over and dropped the rock inside into her open hoof. She gripped it and held it to her heart. Her eyes shot open wide.

"That's right!" She shouted, suddenly perking up. "I forgot! Every couple seasons, us Pies move south for the rock migration!"

"Rock... migration?" Applejack couldn't help but ask, a perplexed look on her face. Pinkie nodded with a wide, nostalgic grin.

"Yeah! My family's followed the rocks for hundreds of years. Its all in that dusty old book in the basement. What's it called? Oh, yeah! 'The Pie Family History'! That was it! Of course, I never actually read it myself, but mom and dad used to tell me about it and--HAAUUUGH!"

Pinkie took in another dramatic rasp of air. She wrapped her arms around Applejack's shoulders and gave her a tight embrace.

"DO YOU KNOW WHAT THIS MEANS!" she shouted excitedly, shaking Applejack back and forth. "IT MEANS WE CAN FIND OUT IF WE'RE RELATED! FOR REALS THIS TIME!"

She put Applejack down, but still held her in a close hug. Applejack shook her head a bit to regain her bearings.

"That's great, sugarcube!" Applejack resounded, returning Pinkie's hug. She pulled back a bit to properly look at Pinkie. "You wanna try writin' your parents to see if they remember anythin' about that?"

"Yeah! But... they don't have a new address yet. We'd usually just have to build a new house every time we moved because of the rock-alanches crushing the southern house between each migration, so it'll be a quite a while before we can write them at all." Pinkie's ecstatic expression faded away. She let go of Applejack, and turned her gaze down.

"Don't look like that, sugarplumb," said Applejack, putting a reassuring hoof on Pinkie's shoulder. She put her head down as well in a moment of deep thought. "Hey! I got an idea! You and me should go down to your family's farm! Have a look through that book ourselves!"

Pinkie's energy re-surged.

"Applejack that's a great idea!" Pinkie shouted. "We'll take the Ponyville Express! Its only about, say... half a day's ride! We'd find out lickety-split! And I could show you around the farm too! Oh, oh! This is so exciting! I have to pack. Cupcakes, pies... What else do I need? Oh! Applejack, you able to leave tomorrow?"

"Yep, I can have all ma chores done by the afternoon!"

"GREAT!" She grabbed Applejack in another titanic hug. Then, she put her down and headed back inside. "I need to finish that cake, and start packing too, so I'll you catch tomorrow. Kay, sis?"

"You got it, sister!"

Applejack returned to Apple Acres later that morning. After finishing her day's worth of chores, she called her family to a pre-dinner meeting around the kitchen table.

"Apples, as ya'll know, my good friend Pinkie Pie has wanted to know for a while whether or not us Pies and Apples are related. Today, she and I discovered a way we can find out. By headin' up to the Pie family's rock farm and finding a history book in her basement, we can finally know for certain. This means a lot to her, so I'd like to leave tomorrow, if that's okay with ya'll."

"Of course!" said Granny smith, in her slightly raspy voice.

"Eeyup," agreed Big McIntosh.

"I wanna go too!" Apple Bloom added. "Maybe if I find what we're lookin' for in that book, I can get ma cutie mark in historical accuracy! Or, ya know, somethin' like that!"

"Not after what happened last time, Apple Bloom," said Applejack, remembering their trip down-river. "This time, I think it'd be best if just me and her went. We can tell ya all about it when we get back."

"Aww-shucks!" Apple Bloom cursed.

Applejack smiled comfortingly, then turned her thoughts to tomorrow. Whatever happens tomorrow, she thought, I'll be there for her. She's ma sister, and nothin's gonna change that.

Author's Note

Thought it'd be good to give them a bit more interaction. And elaborate on that crazy plotline in "Pinkie Apple Pie".