With Discord locked up in a special delivery crate addressed for Princess Celestia, the return trip was the complete opposite of the journey to Canterlot. It was a full out party (Vinyl Scratch had insisted,) and everypony was in an excellent mood.
Twilight set down her glass of root beer, and told Octavia she had to fetch a book from her room. She got up, and walked carefully down the isle of the moving train, grabbing onto seats as she passed to keep her balance. She opened the door to her room and grabbed the book: A Beginner's Guide to Playing the Cello, a book that Octavia had given her a few years ago.
She had never touched a cello, and never wanted to, but that didn't matter. It was just a gesture of friendship when Octavia met Twilight. Twilight was so distracted, she didn't even notice the cloud of pink dust enter the room. It hovered above her and said, "do you really think you'll get away with this?"
Twilight whirled around, dropping the book.
"You've got yourself into something much bigger, something not even Princess Celestia knows about."
Twilight sniffed, and turned on the fan, blowing the pink dust everywhere.
"Watch your step, Twilight! Your brother is-"
The cloud of dust dispersed completely, but Twilight continued yelling, "wait! What? What about my brother? Come back! Come back, Discord!" But he was long gone, not to return for a very long time.
Twilight returned to Octavia's side, and handed her the book. Octavia touched it, and recoiled. "What is this dust all over my book?"
Twilight sighed, "just the remains of an old friend." Octavia gave her a sideways glance, then relaxed, and took the book. "So, did you start playing the cello yet?"
Twilight just burst out laughing.