It's time to poop, Twilight Sparkle.
Twilight looked up from her book. It was time to poop.
She stood up. Turned to face the library's exit. Walked.
As she walked, her legs' movements were mechanical; measured and symmetrical, each of her steps covered the same amount of distance. During the entire minute-long trek to the bathroom, she didn't blink a single time. And her eyes never focused on anything, staring blankly ahead as if she just couldn't move them anymore. Her breathing was even, inhaling and exhaling at the same speed until some seemingly-predetermined, precise lung capacity threshold was met before switching between the two.
Yes, very good. Keep going.
The bathroom door was shut. She stopped in front of it, still facing along the hallway and perpendicular to the actual door. Her right foreleg reached out sideways, blindly, and moved in an unnatural pattern, shaking and sweeping up and down over the surface of the door until it found the handle and pressed it down.
With an echoey click, it opened.
She walked in. Sideways, until she bumped her neck against the door frame and was forced to turn left, now moving backwards.
Her butt faced directly at the toilet like a compass pointing towards magnetic north. The few steps taken to close the distance were just her normal forward walking steps in reverse, which would look strange if anypony was watching.
As soon as her leg bumped the toilet, she reared up and sat on it.
Perfect. Now, poop.
And so she did. Muscles she did not control loosened and began the process. Others tightened, helping the process along. She was a mareionette, a pooppet on invisible strings, with her insides dancing at the behest of a greater being. It was a dance that was required for her. Soon, the evidence of her successful performance was in the toilet bowl itself, ready to be flushed down into the Ponyville sewer system.
She leaned forward, falling gently onto all four hooves, and her hind leg reached back and up, much like with the door handle, until it found the small handle. The satisfying sounds of rushing water and draining pipes filled the room.
Yeeesssssss...
Twilight Sparkle blinked. Shook her head. Sighed and smiled. She was back.
And there was still so much reading to do back at the library.