Diamond Tiara and Silver Spoon are best friends.
Or, at least, they seem to be... until one last straw breaks the facade and Diamond lashes out. Alone and friendless, the rich filly has to make amends, and fast. Now that Diamond has outlived her usefulness, Silver Spoon has no reason not to make good on the threat which tied Diamond to her bidding for the past three years, and Diamond can't hope to deal with the consequences alone.
Even with friends by her side, though, life in Ponyville rarely conforms to expectation, and there are still some ponies determined to make Diamond suffer for her past sins. The truth about her bullying years might just save her, but after three years, things aren't going to be easy. With her father and Cheerilee to guide her, and new friends by her side, Diamond just might make it through this trial in one piece.
Note: the Alternate Universe tag is there for the following small changes from canon: Diamond Tiara's mother died when she was young; the CMC's cutie marks will be different, and Diamond's has a different meaning; and at the start of the story, there is no significant Rich-Apple trade.