The Doctor slowly made his way into his TARDIS. He could feel the regeneration energy coming off of him in small waves. He began to fly the Gallifreyan ship, slowly making his way around the room, pressing every button and flipping every lever he needed to. He sat in the chair and looked at his hands. The Doctor didn't want to regenerate, but he had to.
But he didn't know that this would be his most painful and weirdest regeneration ever.
He felt the golden glow float off into atoms in the air somewhere in the TARDIS. It felt like a part of him was leaving, never to return. His face began to get hot, and he couldn't even see his hands anymore. He stood up from the chair, using up most of what little energy he had left. The warmth he had felt at first began to sting, then became a white-hot pain coursing through his body. He stumbled, losing his concentration on standing up as he just wanted regeneration over with. He hit the console, hitting a lever he didn't ever notice. He steadied himself and closed his eyes. The world turned white, leaving any trace of the TARDIS or anything else he was surrounded by out. He felt the changes happening in his internal side, rebuilding the organs, shifting bloodlines and completely rewriting his every single cell. His insides felt hot, not just because they were healing, but because they were shifting, as if to make room for something extra. They weren't supposed to do that. He screamed, a long, I-sound-like-I'm-dying-but-I'm-really-not kind of scream. On the outside, he could feel himself grow differently, as if he wasn't looking like a human this time. He felt his arms crack into different sockets, ones that shouldn't even be there. He felt his face sort of grow out, as if he suddenly had a muzzle of some sort. His ears grew out, like long donkey's ears, and shift themselves to the side of his head, where his hair was. He felt excruciating pain coming from his back, although he didn't want to know what that was yet. Then it stopped.
It all just stopped. He staggered from the use of how much energy that had been; he'd never used that much energy before for anything. His regeneration had caused chaos in the TARDIS, starting fires and knocking things down. He'd also crashed landed during his regeneration, although where he crash landed he didn't know. The console itself was on fire, and ash was falling from the sides where the wake head caught fire. A bunch of smoke filled the room, and not used to breathing with his new lungs, this didn't help the Doctor one bit.
He'd not even had time to check out his hair; and that was always important. Trying to walk on two legs and realizing he had four, he made his way out of the TARDIS, coughing, and collapsed on the floor of a very confused purple librarian pony. He got up and leaned against the side of the TARDIS. "Huh! A...pony!" He wheezed again. "Hello, I'm the Doctor! Could you, uh, tell me where I am? But not just yet, the process... it's not..."
And with that, he collapsed on the floor, unconscious.
