"It seems pretty simple to perform too. Though I think its usually mean for shrunken ponies..." She looked a bit apprehensive. It was sweet she was concerned about harming you even though she'd just met you.
"Right now, Im willing to try anything!" You said getting to your feet. "What do we have to do?" Twilight propped her spell book up on a podium and read it closely.
"Its just a straight-forward spell, should be easy to cast. You're sure about this though?"
"What have I got to lose? If I dont try Im stuck like this."
"Okay... well, come stand here and I'll give it a whirl." She motioned to the center of the room. You scurried over and stood facing her. Twilight stood behind her podium and started reading aloud from the book. It was inaudible what she was reading but she was intently focussed on it. Her horn began to glow a deep purple and an aura began to spread from it, encasing you in a shell of shimmering light. The light almost seemed to shine right through you as it became brighter and brighter. Almost instantly you could feel yourself growing. You looked down to see the floor getting farther away and your limbs getting longer.
"Its working!" You shouted, looking back to Twilight. Suddenly your attitude changed. Twilight was clearly in pain. Her eyes were clenched tightly and tears were visible in the corners, and she continued reading the spell from memory through clenched teeth. You went to shout to her, to ask her to stop but it was too late. A final blast of light engulfed the room and knocked you off your feet, as well as most of the books from their shelves.
When the smoke finally cleared you found yourself on your knees in a corner of the room, some several feet from where you had been standing. And there. on the other side of the room, was Twilight, unconscious, and looking very worse for ware. You ran to her side, crossing the room in a flash, which caught you off guard for a moment. You checked yourself again and found that you were regular sized again! Well, for the younger self that you were, but it was still an improvement over the rat size you had been earlier.
"Twilight! It worked, well mostly, but Im a normal size now!" You cheered, but Twilight didnt stir. She lay still on the floor. Suddenly you began to panic, and leaned down to her mouth. Faintly you could hear breathing, she was alive but it was only just. "Twilight?! Oh no! What do I do?!"
"Hey! What the heck happened here?!" A shrill voice called from behind. You spun around to see Spike on the staircase. "And who the heck are you? Also, what the heck are you?" At a loss for words you stuttered and rose to your feet, revealing Twilight on the floor behind you. "Twilight!" Spike cried and ran to her side. "What did you do?!"
"I..it...she...it was a spell, I needed help and...she said it was simple." You managed to stammer out. Spike pushed his way past you and hopped up on to the podium. The spell book Twilight had been using somehow had not been even remotely affected by the explosion. Spike quickly read the spell and gasped. He ran back to Twilights side.
"Twilight! Why did you try and do that? You knew that was a dangerous spell. You talked about how tricky that book was all the time!"
"But...she said it was simple..." You sank to your knees, Had you just killed Twilight Sparkle?
No! You were not letting this happen!
"Spike!" You shouted with a fervour that made him jump "Which way to the hospital?" You rushed to Twilight and did your best to lift her on to your shoulders in a weird piggy-back kind of way. It wasnt easy but you got her off the ground and began to follow Spike out of the library and into the night.
To Twilight, the night had been mostly a blur. She vaguely remembered someone coming to her door, someone she couldnt see at first...why couldnt she see him? Then there was some talking and even though she couldnt put a face to the words, something about the voice made her feel happy. He seemed nice, and was well mannered for someone who had been banging on her door in the middle of the night. Then searching through the library...human...a strange word that kept floating in her head... what did human mean? Then she heard her own voice, she was reading something, Then there was a searing pain and blinding light, and then Twilight woke up.
You and Spike had not left Twilights side for days now. Since the night you arrived on the hospital doorstep with her on your back, begging for help, you had been there, waiting for her wake up. Twilights injuries had been serious, but thanks to the speed in which you had arrived, she was well taken care of and was expected to recover fully, even if that meant she spent several days sleeping. The doctors assured you she would be fine, but you were intent on staying with her so the hospital had taken you in and let you stay there while Spike went about letting ponies know what had happened. There you met Twilights friends, and the Princesses in this time, though only briefly. Princess Celestia had even taken you aside to speak with you personally.
"I dont know where you came from, but I am grateful you were able to get my pupil here with such haste. Spike would not have been able to manage on his own, and I fear any other help would have been too late." She gave you a courteous bow. "But I must ask who you are and how you came to be in Twilights home that night." And so you explained as best you could. still leaving out the parts about having seen all this in a show before. You claimed to be from a far off land, which wasnt entirely untrue, and that by some force of magic you had found yourself in Ponyville and Twilight had been kind enough to help you. Celestia smiled and looked back to her student, who lay silently in a hospital bed, surrounded by her friends. "She is a kind hearted pony, so willing and eager to help those in need. I am glad she was able to assist you, and even though she did so at great harm to herself, which I will be speaking to her about when she recovers, I feel that all of this has happened for a reason, so allow me to officially welcome you to Equestria, and I promise we will do our best to discover what has happened to you."
That night, you were quietly falling asleep in the chair you had occupied by Twilights bed for days now, when she gasped and sat up, dazed and confused.