Pinkie Pie lives for her parties, throwing you a party, making you feel special. Just to see you smile happily. She already had Ponyville under her spell, question is where to go next. Of course she goes out, armed to her teeth with her antics.
I just recently started to write stories directly towards the FiM actively, though I have been writing for years, publishing numerous stories at Mibba and the eventual pony story, as far as to the MLP