Sam and Dean first met Glen as he was leaving Madison's house. Madison told them that Glen was very nice and friendly. They later found out that Glen was the one to bite her, however, causing her to become a werewolf. Like Madison, Glen was not aware of his other half and was acting solely on his instincts. He was killed by Dean, who was trying to end the wolf bloodline with Glen and free Madison. Unfortunately, this did not cure Madison of her curse, and she too had to be killed.