Off an old backcountry road somewhere in the southern half of Florida, there's a private aquarium called the Blue Aqua Center. Nestled in a tight space between some cheap tourist motels and a few greasy takeout joints, the place is run by a crazy old long-haired white man with a cane and a handful of "staffers" who smoke reefer, drink on the job, and do only the bare minimum required of their jobs. The animals are mostly treated well and fed regularly, but there is no mistaking the fact that they are there only to make money for the owner, not for scientific research or some other baloney. Every so often, an animal will disappear from the park, sold off to some zoo or private collector for a handsome sum. That's what happened to Gregory's parents.
Gregory was an Atlantic bottlenose dolphin who had spent his entire life at the Aqua Center. He was born in a tank, and as soon as he was old enough to do things for himself, his parents were fished out and taken away from him. He was only a child and knew nothing of how to survive in the wild. The aquarium was the only home he knew.
Yet even then, there were clear signs that Gregory was not just another dolphin. He was exceptionally smart, followed commands without hesitation, and loved to interact with visitors, who enjoyed how he made cheerful noises and danced for them. The owner was quick to notice an opportunity and had Gregory placed in his own tank with no other animals. There, the only things that would keep him company were the humans who came to gawk at him or attend to his basic needs. It was a lonely existence, and Gregory sometimes found himself wishing he didn't have to live at the aquarium anymore.
Eventually, he stopped being so cheerful and happy, and the visitors began to ignore him. The owner was displeased and had the entrance to his tank closed off. Everyone figured it was only a matter of time before he found someone to take the dolphin off his hands.
Alone, Gregory started to undergo strange physiological changes. His flippers and tail fins slowly expanded and separated into limbs, until he had a pair of arms and hands with four fingers and a thumb. He also gained a pair of human-like legs, which initially made it harder for him to swim until he figured out how to use his fins and feet together. His chest became muscled and toned with nippled pecs and a six-pack, and his human genitals gained an impressive length (not to mention it was much easier for him to masturbate with hands). The only things that he kept from when he was just a dolphin were his head, with its circular ears, snout, and blowhole, his back and legs fins, and his gray-colored rubbery skin.
But nothing marked his transition from an animal to an anthropomorphic dolphin more than the sudden growth of his brain and intellect. Suddenly, he could understand every word that had ever been spoken in his presence, and he began to teach himself how to speak. He became aware of his environment and its limits. But most importantly, he realized that he needed to escape. The owner had been dithering on selling him off, but if he or his staffers became aware that they now had in their possession a rare specimen that any scientific institution would pay through the nose to own, his fate would be sealed.
Over the next few weeks, he made his plan. The first thing he did was alter his daily movements so that when the staffers came to toss food in his tank or do some cleaning, they didn't notice him (something made painfully easy by the constant drunkenness and drug highs). Then he found things to aid in his escape. A map someone had carelessly left lying around revealed that the Aqua Center was close to an open river that was deep enough for him to swim in. Some muck spread on the glass would obscure the view of his tank and made it harder to notice that he was gone, at least for a day or two. At night, Gregory climbed out of the tank and practiced breathing, walking with quiet footsteps, and sneaking around. He contemplated stealing some clothes for a disguise, but then decided it would be easier to just stay naked.
Finally, he put his plan into action. It was late at night, and the owner was asleep. The Aqua Center had only a handful of unreliable security cameras, and three or four men patrolling the grounds with flashlights. Gregory climbed out and quietly left the exhibition hall. From there, he waited until a guard opened an exit to go piss outside, and slipped around him until he reached the fence. Scaling it proved to be a bit difficult and he nearly cut himself on the sharp edges of the metal, but once he was over, he was finally free of his owner.
The naked dolphin man made his way to the river. There, he could figure out where to go next.