Derpy woke up earlier than usual, and decided to suprise her new friend with a nice breakfast of toast with apple jam, which she had gotten from the Apple family after helping fix their barn. She popped the bread into the toaster, and then left to set the table. She could smell something funny. Not funny ha-ha, but funny in the sense that the toast was going to be ruined shortly. She decided the toaster knew what it was doing, and continued setting out paper plates and plastic cups. She wasn't allowed to have ceramic plates or glass cups, they were breakable.
The Doctor woke up on the couch, the smell of something burning coming from the kitchen. He jumped up and ran to the kitchen, to find Derpy staring at the toaster, which was emitting thick, black smoke. After airing out the kitchen and throwing away the ruined toaster, they went to Sugarcube Corner for a breakfast muffin. They recieved two more free muffins, which was very strange. Oh well, he thought. A muffin is a muffin. They each ate their muffins. Bran for him, purple for her. He was suspecting a theme going on with these muffins.
After the short breakfast, he left Derpy at Sugarcube Corner. She apparently had to work that day to pay for the muffins. He was fine with that, as he needed to check on the TARDIS. He had been thinking about just ditching this world and going back to earth, but after getting to know some ponies, he found it might be difficult to leave them behind, namely Derpy. He shook his head and stepped inside. He activated it and set the destination for Earth,January 2013. He went nowhere. He stepped outside and kicked the phonebox.
"Damnit!" he cursed, unable to suppress his dissappointment in the machine. He walked back to the cafe to look for Derpy.
And found her in a room who's floor was covered with soap suds, which was rapidly rising to fill the room. Already it was past her fetlocks. Derpy looked ashamed.
"I'm sorry!" she cried, "I tried really really hard, I promise!" She was visibly upset and seemed to think it was her fault. He comforted her and told her it wasn't her fault. They cleaned up the bubbles before apologizing to the Cakes. They still paid her for the work she did, but didn't look too happy about Derpy having flooded their kitchen.
"I can't do anything right," Derpy sniffled. she was crying about having ruined something for the second time that day. The Doctor thought of something that might cheer her up.
"You showed me your world, why don't you let me show you mine?" He looked to Derpy to see her response. She looked... scared. Scared but intrigued.
"I dunno. I gotta work later. Ponies won't be too happy if their mail isn't delivered on time." She was skeptical.
"You'll be back before they realized you were gone, promise." He actually really wanted to show her his world. He found he cared deeply for this mare, crazy as it seemed. He wanted to see how she would react to Earth, to human beings.
Derpy thought for a moment, then asked the question that would determine whether or not they left.
"Do they have muffins there?"