"Fluttershy"? "where are you?" "i'm here replied a tiny voice the voice that must belong to Fluttershy Twilight walked into a dimly lit room in which Fluttershy laid on her couch delicately fraily while Applejack held her hoof in hers. Pinkie pie shot a worried glance at Twilight "what... what happened"? Said Twilight puzzled "umm is ... Fluttershy ok?" "no" replied Fluttershy very quietly "I know i'm dying and I probably won't make it" she said sadly "Oh Fluttershy don't think that way "! interrupted Applejack "but Applejack was interrupted by Fluttershy again "I just want say" she said "you were the best friends I ever had" she said and with that Fluttershy took one finally breath and closed her eyes forever.
Applejack whom was holding her hoof shook her head because Fluttershy's hoof was as cold as ice.
"Fluttershy"?said Twilight with tears in her eyes "shes gone twilight" said Applejack she too was crying. This gave Twilight a sad dark part of herself that at this moment was sad and isolated from everything else. To everyone else in the room especially Applejack saw that Twilight's look was indeed silent , isolated and sad in a dark kind of way. This worried Applejack.
When they left that morning Twilight's complete personality completely changed. She still was a total book worm but the books she read were much more dark, sad , and grim. In her mind she grew a grimmer, isolated, and dark part to turn her into a new version of Twilight that was not friendly nor purely... good.