After another muffin (or three, Derpy wasn't sure about the abundance of muffins that The Doctor had talked about, so she wanted to savor her "last" muffins), the not-so-dynamic duo set out to time travel to Earth. Derpy straightened her saddle bag and looked at the TARDIS.
"And you're sure its safe? And that it has muffins?" She cared mostly about the muffins, but the safety was another big factor.
The Doctor smiled softly. They had already spoken of the safety, the way it worked, but mostly about the muffins. He remembered her open mouthed awe at the thought of whole stores with nothing but muffins. That you could buy muffin mixes! That new kinds of muffins were invented everyday!
"There is no need to worry Derpy, it's completely safe. You just step in and it takes you to where we're going!" He did't feel like explaining the whole process again.
She shook her head and smiled at him, trying really really hard to focus her eyes on him. She found that even though she was scared of this "Earth" place, she didn't want to be here without him. She felt weird about this pony. Not weird bad, but weird good, if weird good was an actual thing. She trusted him, and being near him made her feel special. Not special like when other ponies called her special, but special like she mattered to him, like he really liked her. She didn't know it, and he tried to hide it, but he did really like her. They looked to eachother, smiled, and then stepped inside.
The Doctor raised up on his toes and stretched his arms and legs, feeling good about being human again. He heard a thud, and looked beside him to see Derpy lying on the ground. She looked alright, and rather attractive in her human form, with blonde hair and pale skin, and clad in a grey sweater and sweatpants. Her eyes remained their golden-amber color, and were still "derpy". Her saddlebags turned into a leather backpack, and she had a necklace who's charm depicted a cluster of bubbles, her cutie mark.
"I can't see! I can't stand! Where are we?!?!" Derpy cried. She was scared, and in a new form that was totally alien to her. "My wings!" she clawed at her back, and tried to find her wings. She removed her sweatshirt and spun about, trying to see her wings. They were no longer wings, merely a tattoo of black angel wings on her shoulders and back. She appeared to be a fully formed human female, He could see that after she had removed her sweater, but he shook his head, helped her up and put her sweater back on her. He looked up to see Amy and Rory staring at them in shock. He picked Derpy up and looked to them.
"Amy, Rory," he said tentatively, "Meet Derpy."