"Pixie, you excited for the reunion?"
"Yeah! Ahm lookin' forward to meetin' all my cousins!"
~~
"WHAT is going on here?"
"Look, Frost-"
"Who in all of Tartarus is that?"
Pixie glanced around nervously "Me?"
"No, that unicorn."
"Frost, that is my wife. Leave us alone."
"Aunt AJ, is that your daughter?" Frostbite pointed to Pixie with a snarl "What's that cutie mark?"
"Well, I got it when I saved-"
"I don't care, Princess."
"FROSTBITE APPLE!"
"I'm sorry, is something going on?" Silverlay turned to her wife- "should me and Pixie go somewhere else?"
"Yeah, get your prissy Canterlot flank away from us apples!"
Pixie got up and brushed herself off. "Hey! You DO NOT talk to my family like that!"
Frost chuckled as Applejack and Silverlay started to walk away- but stopped abruptly. Her eyes grew wide as she glanced at her aunt- "Aunt AJ, are you... pregnant?"
~~
Frost's parents are Apple Brown Betty and some random stallion. She was raised thinking that only Earth Ponies can be apples, and all others don't deserve to be part of their family. Her and Pixie end up mortal enemies, always at eachother's throats.
Applejack got pregnant when Pixie was an a teenager, so Pixie was old enough to know what was going on.
Eventually Frost goes as far as getting a unicorn that I haven't introduced yet to perform a spell that will go back in time and split Silverlay and Applejack so the apple family can stay all earth ponies. YOULL SEE WHAT HAPPENS!!