Stephen Phelps was a math teacher at Marshall High School.
At some point, he started working at Marshall High School in Sioux Falls, South Dakota. Stephen was loved by everyone, students, faculty and parents.
He eventually became the math teacher of Annie "Alex" Jones and believed in her potential. Stephen became a big role model in Alex's life, helping her to change her behavior for the better. According to Alex, he encouraged Alex to quit the soccer team and join the math team instead.
One night, after joking with Alex about an upcoming math test, Stephen returned to his car to go home and appeared to sense that someone might be stalking him. Shrugging it off, Stephen went to get in his car, only to be attacked by one of his students, Henry. Henry was now a vampire working with Richard Beesome to get revenge upon Alex. Henry snapped Stephen's neck and hung his body upside down from the flagpole.
The next morning, his body was "found" by Richard in his role as the janitor. Stephen's murder drew the attention of local Sheriff Jody Mills as well as hunters Sam and Dean Winchester. While the Winchesters and Jody had been skeptical of Claire Novak's insistence that there was a monster in town, the circumstances of Stephen's murder proved her right. Richard, though he had an alibi, appeared to care less about Stephen's murder and this drew the hunters attention to Richard as a suspect.
After kidnapping Jody, Alex and Claire, Richard stated that Stephen's murder was part of his revenge plot against Alex: kill her favorite teacher. However, Richard thought that Henry, who "had a real mean-streak" went too far by hanging Stephen's body from the flagpole. Henry was unrepentant, feeling that it had been a surefire way to get Alex's attention.