I don't own them. It's all JK Rowling's. I'm just borrowing them for the moment. Italicised text is quoted from Harry Potter and the Sorcerer's Stone, US version p. 28.
A very strange thing happened at the Reptile House at the zoo. As a fat, blond-haired boy and a boy with a rat-like face approached the enclosure, the glass separating the snakes from the people disappeared. A boa constrictor slithered out from the enclosure, causing people to scream and run as far away from the snake as possible. It looked at the small boy with the black messy hair and the glasses. "Brazil, here I come … Thanksss, amigo," it said.
The boy blinked at the snake. "You're welcome?" he answered hesitantly.
The snake continued on its journey toward the exit and on to freedom. But what did it know of true freedom: it was bred in the zoo and was around its human handlers for its entire life. What was it going to do for food? It would have to forage for food, like any other snake living in the wild. At least there wouldn't be any more annoying people tapping at the glass, wondering why it wasn't moving. But there wouldn't be any other snakes to keep it company. There wouldn't be any humans to ensure it kept warm, watered, and well-fed. There might be predators out there that would want to do it harm.
The snake stopped its motion and turned to look back at the zoo it abandoned. Was it worth losing all of those comfortable things just to find a place that was just a meaningless name?
The boa constrictor felt the ground vibrating, and then it heard a familiar voice.
"There you are," the voice said. "You silly snake. I have no idea how your glass vanished, but we must get you back to your enclosure. Come along now."
The snake gratefully coiled itself around the handler's arm and slithered along his back toward his other arm. "Thanksss, amigo," it said. "I think I do want to go back home now."
A/N: Prompt issued by HermioneWeasley1972: Write about the boa constrictor's adventures after Harry set him free. Did he get to Brazil? Thanks go to ladyinthecloak for the beta-reading.