Just An Average Trip to Equestria

Tick. Tock. Tick. Tock. Tick. Tock. Tick. Tock. Tick. Tock. Tick. Tock. Tick. Tock. Tick. Tock. Tick. Tock. Big. Clock. So. Slow. Won't. Stop. Tick. Tock. Tick. Tock. Equestria. Far. Away. Can't. Go. Not. Time. Tick. Tock...
Aaaaaaaaaaaaaaaaaaaaaaaaaaaa!
Aaaaaaaaaaaaaaaaaaaaaaaaaaa!

Sunset woke up suddenly and looked around the classroom. The teacher was droning on about some maths equation, but nobody was listening. The stifling heat of the summer day was making everyone sleepy, and they were all thinking about the summer holidays. Some would stay at home with their families, some would be going to foreign, exotic countries. Technically, Sunset was doing both. She had all her things ready at her bungalow for a nice long fortnight. She would spend her time with Twilight Sparkle and her friends, and visit Celestia in Canterlot. According to what was written in her journal, her pony friends needed a break as much as she did.

"Miss Shimmer, would you be able to tell me the answer to this question or do you need to have a long nap during the holidays?" barked the teacher. The class broke out into laughter.
"I'd much rather the second option, sir," she replied. "And you shouldn't snap at a student who saved your life from two angry demons a month ago."
Now the class were laughing at him.
"Fair enough, Shimmer. Next time you refuse to pay attention, I will give you holiday homework."
"No can do, sir. I'll be going to Equestria to see the other Twilight Sparkle, and there's a lot of stuff we need to do. Plus, there aren't any pens. I could use a quill and ink, but the ink would seep through the pages of my book and destroy it."
He sighed. "You are intelligent, Shimmer, I'll give you that. If only you put as much effort into your work as your," he hesitated, "magic."

At the end of the school day, Sunset did not go straight to Equestria. She had to say goodbye to her friends. How to do that? Go to Sugarcube Corner and eat a donut each. They each talked about what they would be doing. Twilight would be going to a festival in a few days - which was held in the grounds of a university that specialised in science. Pinkie and her boyfriend Cloudy Sky were going on a cruise around the world. Rainbow Dash was going to run a marathon for charity, and Rarity and Fluttershy were going to support her before heading off on a horse-riding holiday. Applejack was spending the entire six weeks on the family farm. She didn't seem to mind. She was actually looking forward to it. Everyone was looking forward to the holidays.
"So, how're you spendin' your 'oliday Sunset?" asked Applejack.
"It's a surprise," she replied. "I know I'll spend most of my time in Ponyville, but I don't know what's in store. If I hazard a guess, the other Fluttershy will take me into the woods and the other Rarity will take me to the spa and get me into an amazing outfit for the party that the other Pinkie Pie has organised. The rest of the time will be spent relaxing," she sighed in relief and happiness. "Between fighting off two demons here - no offence to Pinkie and Cloudy-"
"None taken," they said together.
"Telling my own demon where it stands, and adjusting to the Dazzlings as friends, I could do with some relax-in-Equestria-with-my-other-friends time."
"Speaking of the Dazzlings," said Rainbow Dash, "Will they be there?"
Sunset bit her lip. "They have a schedule. I'm probably going to run into at least one of them. I hope it's Sonata, she still owes me a burrito. Let's see her face when she finds out how expensive eating out is in Canterlot."
Everyone laughed. Sunset looked at the clock on the wall.
"Dammit," she said, "gotta go. Twilight closes the portal in ten minutes. Rainbow, I might need a magic piggyback."
"Nope. You'll break my back before the marathon. Well, you and your backpack."
Everyone hugged and wished each other well. Sunset gave each of them a notebook.
"They work in the same way as my journal. Not as big. Just for the holidays. When I'm in this world, we can use Skype or that stupid site Grapevine. Eight minutes. Bye." She ran out of the café.

She took a taxi home. Three minutes. She scrawled in her journal, need 15 more minutes, then changed into a new outfit. Even though she would not be wearing them in Equestria, she didn't want to be in smelly clothes when she returned. She switched backpacks, and packed her journal and a notebook identical to her friends' ones into the new backpack. Her motorbike was in the garage, locked away and safe. In pony years, she would turn nineteen in August, so she was technically allowed to drive. She had passed her driving tests with ease, so by law it didn't matter. Twelve minutes. She hauled the backpack on, left the bungalow, locked the door and legged it back to Canterlot High School. Five minutes. She yelled a war cry and ran through the portal: a statue of a horse on its hind legs.

All of a sudden she was in Equestria and everypony was screaming. She could not understand a word of what they were saying. She counted. Applejack, Fluttershy, Rarity, Rainbow Dash, Pinkie Pie, Princess Twilight Sparkle, Spike the dragon, Princess Celestia and Princess Luna, Starswirl the Bearded, a pony called Starlight Glimmer she had once met, a yellow stallion with called Sunburst, Adagio Dazzle, Aria Blaze and Sonata Dusk ("Yes," she whispered), all with new necklaces.
"Woah, what does any of that mean?" she yelled. Everyone instantly stopped screaming at each other. The problem: they stayed silent and did not tell her anything. "Are you going to let me stand here without a clue what's going on and looking like an idiot?" she shouted, flapping her huge yellow wings.

Wings. She had wings. She was an alicorn. She was a princess.

How in Starswirl's hat did she become an alicorn?!