Pinkie decides to reveal her past to Twilight - her tough, unfriendly past.
Twilight decides to tell Pinkie/her own friends about it, to attempt to help Pinkie.
NUTSHELL:
Pinkie discusses her problematic past. Twilight tries to help by comforting her etc. Rota is introduced between Fluttershy, Rarity and Twilight.
This story is short, but well-written.
Keep going with it! :D