In Season 3, Jordan Parrish is a new deputy at the Beacon Hills Sheriff Station under Sheriff Stilinski. He is eventually promoted to Deputy Sheriff. In Season 4, Parrish investigates a series of murders that are revealed to be actually assassinations. He meets Lydia Martin, then learns he is on the hit list, the Deadpool. His fellow Deputy-turned-dirty Deputy Haigh attempts to kill him for his bounty by setting him on fire, but he survives. Parrish is informed of the supernatural world by Scott's Pack, learning he himself is a supernatural creature and that he was drawn to Beacon Hills by the Nemeton. He helps the pack protect the remaining targets, saves Chris Argent from death and assists them in their battle against Peter Hale and Kate Argent. In Season 5, Parrish becomes close friends with Lydia, teaching her hand-to-hand combat. During the Dread Doctors' reign of terror on Beacon Hills, when the Chimeras are killed off, Parrish's supernatural nature comes forward and takes over him, taking the corpses to the Nemeton going against his legal obligation to his conflict. He discovers he is a hellhound, an avatar for the amortal hellhound spirit , a Guardian of the Supernatural and is the foretold enemy of the revived Beast of Gévaudan. With Stilinski, the pack and Chris' support, Jordan eventually resolves his inner conflict with the hellhound, accepts his supernatural destiny and alongside Scott's pack, vanquishes the Beast.
Jordan Parrish is an immensely resourceful, diligent and well-adjusted individual who's easy to talk to and get along with. An ex-soldier, now a sheriff's deputy, Parrish has a firm sense of duty and honor, and moral compass, dedicated to serving and protecting his community while upholding the law. Despite his age, Parrish displays great fortitude, has strong protective instincts like Sheriff Stilinski and Scott McCall and is strong-willed having shot a criminal dead in defence of a third-party victim, Brunski when he was about to murder Lydia Martin.
Parrish displays an open mind after surviving an explosion while serving in Afghanistan. He comes to grips with the idea that Lydia Martin is psychic, and when he's introduced to the supernatural world and becomes an ally of Scott's Pack, he holds himself well and willfully assists and joins their role in protecting Beacon Hills from dangerous threats. When he discovers his actions while being a hellhound, he firmly sticks to the his morals by having himself incarcerated to protect the people around him.
As a hellhound, Parrish is undeterred by what he sees as his mission to protect the supernatural world as part of the Wild Hunt, guarding the secrcy even if it means assaulting innocent bystanders.
Parrish is on the Deadpool hit list, although he has not displayed any powers as of yet. His reveal as a supernatural creature was foreshadowed in 3x23 - Insatiable when he told Sheriff Stilinski that he was drawn to Beacon Hills, using the same phrasing that Deaton used to explain what powering the nemeton would do.
Episode 4x09 - Perishable opens with Parrish tied into his cruiser. Deputy Haigh doused him with gasoline and then lights him on fire in order to collect his bounty. Somehow, Parrish doesn't die in the flames. He walks into the sheriff station covered in only soot and proceeds to beat Haigh into submission. Lydia and Scott take Jordan to see Derek, but Derek doesn't know what kind of supernatural he might be.
When Parrish goes to the sewer to save Chris, his eyes flash an orange color while they strain to bend the rebar that will release Chris from captivity.