Friendship Is Betrayal/Tear Jerker

"Twilight: I'll never forget her overjoyous grin."
 * Under Nightmare Moon's Mind Rape, Twilight is forced to relive the events leading up to her meeting the princess... and the reason why she despises her so.


 * Pinkie Pie's past is no better.
 * Celestia confronting Luna, giving her a "The Reason You Suck" Speech, and . All while still calling her "my beloved Luna".