The gym trainer stood behind Peter, straining to tighten the swap collar around his thick neck. As the two ends clicked together, there was a hum from the electronics woven into the pink leather, and a strange, straight line of sensation cut through his neck, as if it had been cleaved painlessly in two. The woman grasped his head firmly on either side, twisted, and...

Pop! His head twisted clean off. She flipped him around in her hands to see his headless body, still somehow standing with its arms held limply by its side.

"I really have let myself go, haven't I?" Peter said, the sight of his heavyset body somehow more visceral this way than in a mirror. "Hey, I can talk? But I don't have any lungs. How does that work?"

The trainer merely laughed and set him down on the floor, resting on one ear. His head rolled, nose down. The floor didn't look to have been cleaned in a long time and had the same musky, sweaty odour of the rest of the gym, moreso with his face pressed against it.

"Now let's find your partner," the trainer said energetically, putting two fingers in her mouth and giving a shrill whistle.

A Doberman in a matching pink swap collar padded obediently across the gym floor. It stooped to sniff Peter's head and gave an excited yip as its master neatly twisted its canine head off. As she screwed the severed head onto Peter's body, his limbs twitched, the posture hunching. With remarkable energy, his body bounded away on all fours towards one of the treadmills, belly rippling. A painful-sounding wheeze was soon emanating from the dog's slathering jaws, though it seemed unfazed by it.

"You're lucky. Nova is one of our most enthusiastic puppies. She'll run and run until she drops. She'll have you as lean as a whippet in no time!" the trainer said, picking up Peter's head and placing it on the smooth, fleshy nub of the dog's vacant neck. Sensation flooded in; a muscular, furred body whose blood pumped with youthful energy. He could feel his tail wagging nervously and the plastic gym mats beneath his canine claws. The smell of dog was potent and inescapable. His sneezed. Already his eyes were watering from his allergies. To think he'd paid for two weeks of this.

Slowly he lowered his head, peeking between his front legs to his hindquarters. When he'd requested a swap trainer, he'd made few stipulations. He was a bitch. That would take some getting used to.