was bitten by a pureblood werewolf. Initially struggling to control his wolf side, he soon met Derek Hale, a strange man with a dark past who was also a pureblood werewolf. Then, he met Erica, a girl who started as a bullying victim, but became a beautiful Succubus after making a deal with Lillith, Queen of Demons. Seth and Erica became a couple, despite Derek warning that Erica would be the death of him. After Erica was seemingly buried alive by Allison Argent, Seth decapitated her out of anger, only to learn that she was the only person that knew where Erica was buried. Traumatized, Seth left Beacon Hills and moved to the much more quiet Mystic Falls, planning to start over and get over Erica's supposed death.
Shortly after becoming a werewolf after being bitten, he wanted to be a pureblood werewolf so he could control himself. After being put through a ritual (in which he had to drink the blood of King Lycaon himself), he was now a pureblood werewolf.
Seth is played by Tyler Posey.
Seth was born in 1996 to Jennny Peters, a nurse at Beacon Hills Memorial Hospital, and Raph Michaels, a special agent with the FBI. Seth was afflicted with asthma from a young age, which only became more severe as he got older. When he was in elementary school, his alcoholic father got drunk one night and got into a fight with Jenny, and when Seth went into the hall, he grabbed Seth by the wrist to force him back into his room. When Seth reflexively pulled away from him, he was accidentally pushed down the stairs by Raph, a fall which knocked him unconscious for twenty seconds or so.
Afterward, Seth didn't remember a thing, but Jenny was so furious that she ordered her husband to leave. She only intended to throw a drunk man out of the house, but, in time, Rafael became so ashamed that he left the family completely. Though Scott did spend some time living with Rafael at first, he eventually moved back in with his mother, and Rafael discontinued his contact with Seth and Jenny before moving to San Francisco to work at their FBI field office, an act for which Seth resented him until he reached high school.
When Seth was a young child, he was taking his small dog Roxie for a walk when the two were attacked by a rabid doberman. The stress of the event caused Scott to have such a severe asthma attack that he was sent to the hospital, and his dog ultimately died from her injuries. For some unknown reason, this memory became repressed in his mind, either because of how traumatic it was or because the doctors at the hospital suppressed it.
Being raised by a single mother for most of his childhood, Seth saw how hard his mom had to work to keep the household running, so when he was old enough, he began working as an assistant zookeeper to make extra money so they could make an at least decent living. Once he entered high school, Seth joined the soccer team with his best friend of many years, Paige, though they rarely ever played due to their lack of athletic prowess.