He believes in Lydia's psychic powers and seems comfortable with the idea of the supernatural. 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.
He is 24.
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. They haven't checked the bestiary for answers because apparently Chris now has the only copy, and Parrish doesn't know what he might be himself.
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. Parrish also says that he's been spending time with Lydia, who told him all about Chris and Allison.
Parrish uses an HTC cell phone.