Back in Ponyville that night, Twilight had the library to herself. Spike still being a little scared at her reaction earlier that day and seeing how, to his annoyance, Sweetie Belle was staying with Rarity, was over at Sweet Apple Acres with Applejack.
All the books were neatly put back on the shelves in the correct and proper places just like they were before Rainbow Dash knocked them all down, and Twilight was getting into bed.
"Goodnight Spike"
...
"Oh yeah...," Twilight remembered that she kicked him out with the rest of her friends. Then she went over to her trunk and got out her fillyhood bed-time toy Smarty Pants and went back to bed. After saying goodnight to Smarty Pants she closed her eyes and fell asleep.
Up in Canterlot, after she had raised the moon, Luna began one of the other powers she had, being the Princess of the Night, and started dream walking until she found the door to Twilight Sparkle.
"Let's see if I still have it in me," she said, eyes turning white as she went though the door.
Twilight was having the best dream ever. She was walking down the aisle in a beautiful white wedding dress up to the alter towards Flash Sentry.
Celestia being the prepony cleared her throat as Twilight stepped up next to Flash. "Mares and Gentle-colts," she began "We are gathered here today to bind Twilight Sparkle and Flash Sentry in the everlasting line of marriage. If there is anyone here who thinks these two should not be wed let them speak now or forever hold their peace."
"I do," a voice called out but no one seemed to hear it apart from Twilight. In fact everyone was frozen, all apart from...
"Princess Luna?" Twilight asked still looking around "What are you doing here? Are you dream walking? What gives?" Twilight was asking getting annoyed that her best ever dream was being interrupted.
"Nice to see you too Twilight," Luna said smirking just a bit. "But to answer your questions; Yes, I am dream walking, and I'm doing it because my Sister," she said pointing to Twilight's dream Celestia, "heard that you wished that you never came to Ponyville, so I have come to show you what it would be if that reality was this one."
Then the world around them began to ripple as though it were a puddle of water.
They were outside, in the dark, with black crystals all over the place, and everything was upside down.
Ducking to avoid some flying pigs, Twilight asked "Er... Princess what happened here?"
"Well, this is a world where you never went to Ponyville. In doing that you never met your friends, and so never retrieved the Elements of Harmony," Luna began "With the Elements not retrieved, there was no way to defeat Nightmare Moon, or Discord when they returned. And because you had no friends to go with you to the Crystal Empire to keep the fair going while you looked for the heart, even though Spike got it out to them in time, the Crystal Ponies were too scared to bind their will-powers for it to work when Sombra attacked."
"Well, well. What do we have here?" a rough villainous voice rang out behind them. "Another Unicorn I can use to bring even more treasure out of my Crystal mines."
Spinning around Twilight saw none other than King Sombra, horn bubbling black and fangs bared. She did the only thing she could think of. She ran.
"Oh no you don't," he called after her shooting streams of dark magic at her, barely avoiding her until at last he got a direct hit and she was knocked out.