Pinkie was born in Cloudsdale, on a quiet snowflake farm away from the main cities. she had a sibling, named Surprise Pie, but her parents put both her and her sister up for adoption because they couldn’t support either of them. Surprise was adopted in Cloudsdale almost immediately, but Pinkie realized that she was too hyperactive for most families, and she thought she was never going to be adopted. so, she ran away and took the next sky carriage to Equestria, ending up at Ponyville after she bolted into the woods and ran for days and days until she just couldn’t anymore. she passed out on the doorstep of Chiffon Swirl and Carrot Cake’s place, Sugarcube Corner. Chiffon found her and brought her in, incredibly worried for the filly. after Pinkie woke up and was taken care of, Chiffon couldn’t help but love the adorable bouncy filly, and the couple ended up adopting Pinkie as their daughter. it was there at Sugarcube Corner that Pinkie discovered her talent for partying, after participating in a birthday party that was being held there for a young filly named Applejack.
 
Pinkie knew Applejack’s mother, Sweet Blossom (and by extension, Applejack), because she would work there at the bakery often with Chiffon Swirl, helping her make apple themed treats. she was very upset when she learned that the sweet mare had died, and mourned with Applejack at the farm. she, along with (the now married) Mrs. Cup Cake and Mr. Cake were invited to the private funeral for Sweet Blossom, and Applejack and Pinkie Pie have been friends ever since.
 
at some point, Maud and her siblings visited Ponyville from their rock farm home, and although most of the Quartz family didn’t really like Pinkie because she was too loud and obnoxious, Maud ended up becoming very close to Pinkie, and the two would send each other letters and rock candy necklaces (and still do to this day).