Cydne lives in the swamp that borders the Dearly Farm. Despite the fact that he seldom leaves the farm, he has proven time and time again that he is a force to be reckoned with whenever creatures do venture into the swamp; though Cydne has been known to leave the swamp if he has a good reason. Due to his fierce nature, Swamp Rat often hires Cydne along with Steven in order to intimidate people into seeing things his way, though Cydne enjoys helping his boss out because he realizes that he'll get the chance to devour some creatures in the process.
Cydne appears in "It's a Swamp Thing", where Swamp Rat tells the Dalmatians that he sold the Colonel's scarf to Cydne. When Spot tries to ask him about it, Cydne figures they're charity collectors and comments how "[He] gave at the office." Cadpig then tries to talk to him, claiming that Cydne has inner pains and suggests that they have a group hug. Seeing this as an opportunity to get some food, Cydne plays along by wrapping himself around the pups and nearly squeezing them to death. He then tells them how he sold the scarf to Steven before the pups pop out from his grip, and he gets knotted up as a result, claiming them to be "sssslippery little ssssuckers."
Cydne's largest role in the series was in "Bad to the Bone", where Rolly fakes a fight with Cydne Snake to get Mooch's gang off his back, which causes Mooch to let Rolly join his team. However, Rolly soon manages to alienate his true friends so that he can remain popular. As Dumpling is searching the swamp for some mushrooms, she is caught in Cydne's coils, and she tells him what Rolly's new title is. He later confronts and restrains Rolly on the Dearly Farm and gets him to confess that the fight was really with an empty snakeskin in front of all the Dalmatians. He lets Rolly loose after that before commenting that the earring didn't work as a good look for Rolly.