Twilight bursts back through the doors of the library. "This is bad, this is very
very bad--" She has a hunch she knows what's the cause of all this, and if she's right...
Spike is close behind her. "What's goin' on? Why is this happening??"
"Last night, when you were taking one of your seven-hour bubble baths,
I got a special delivery from the Princess," Twilight explains. "It was an old spellbook belonging to Star Swirl the Bearded--"
"That crazy grandpa pony you dressed up for on Nightmare Night?"
"--the
famous unicorn wizard, yes," says Twilight, gritting her teeth. "There was an incomplete spell in the back of the book that Princess Celestia wanted me to finish. I cast the spell so I could find out what it was, but nothing seemed to happen... but now I know something
did happen!"
She gestures toward the display case containing the Elements of Harmony. Something is different. The colors of five of the six gems--all except for Twilight's own--have somehow been mixed up. "The spell has changed the Elements of Harmony! That must be why their cutie marks are all wrong!"
"So just cast a counterspell to switch 'em back," suggests Spike.
Twilight flips through the notebook frantically, but-- "There
is no counterspell!"
"Why don't you just use that memory spell you used to fix everypony when Discord was here?"
Twilight shakes her head. "It's not their memories, Spike. It's their
true selves that have been altered."
"Zecora's cure for the cutie pox?"
"That won't work either!" Twilight wails. She shoves the notebook into Spike's claws and walks away, frustrated and defeated.
"...maybe it won't be so bad," offers Spike. "Maybe your friends will grow to like their new lives."
Twilight sighs. "No, Spike. They're not who they were meant to be anymore. Their destinies are now changed... and it's all my fault."