Second Mane 6 member for my headcanon series!  
Pinkie Pie is a mare of many talents and occupations, them being: Element of Laughter, Professional Party Pony Planner, and Friendship Ambassador to the Yak Kingdom. The pink pony of fame has humble beginnings, being raised on her father’s rock farm with her 3 sisters. After gaining her cutie mark, however, it became more and more difficult for her parents to tolerate her newfound hyperactivity and strange behavior. The one party was fine, but Pinkie seemed to want to do one at least three times a week, which none of them had the time or energy for.
 
After a particularly nasty bout of yelling from her father, Pinkie decided to leave the rock farm. It’s not that she really wanted to, but it was the only way she would be able to harness her special talent and do what she loved. She was a preteen at this point, and Maud offered help her find a place to stay. During their trip together, they found the Cakes, a nice couple of earth ponies who needed some extra help around their bakery. Pinkie excitedly took them up on the offer, and has stayed at Sugarcube Corner ever since. Then, after meeting the others of the mane six, Pound and Pumpkin Cake came along, expanding the new family she had found. Pinkie Pie is an excellent older sister/cousin figure to the twins, and has been their go-to gal for talking about stuff that would be awkward with their parents. Pinkie was actually the first pony Pumpkin came out to as a lesbian, since she just needed a little reassurance and support before coming out to her parents.
 
After the defeat of the Storm King, Pinkie quickly became BFFs and pen pals with Princess Skystar, and eagerly wrote to the hippogriff whenever anything even mildly interesting happened in town. It wasn’t long before the hippogriff princess started visiting Ponyville and Pinkie regularly, since she wanted to see what the town was like. It wasn’t long before their relationship evolved into a romance, and, after getting a blessing from Queen Novo, had the biggest, wildest, craziest wedding party Ponyville (and likely all of Equestria) had ever seen.
 
Two years later, they had Caramel Crunch, one of the first hippogriff/pony hybrids in Equestria. Pinkie has dubbed him a “ponygriff”. Four years after that, the couple adopted Gumball, an orphan colt from Canterlot who has since become a candy making master. The family of four, plus the Cakes, all live in an expanded Sugarcube Corner.