Dean Winchester is a human and hunter, formerly a demon, a member of the Men of Letters with his brother Sam and one of the lead protagonists, also a temporary antagonist, in Supernatural. He and his brother are members of the Winchester and Campbell families, and Dean is also the destined vessel of the archangel Michael. He and Sam are also the surrogate sons of Bobby Singer. Dean is best friends with the angel Castiel, close friends with the late prophet Kevin Tran and reluctant ally of Crowley. Dean has an ex-girlfriend, Lisa Braeden, who he lived with for a year when Sam was in Hell. She has a child named Ben, who Dean acted as a father for. Dean is also the former apprentice of Alastair. Both Dean and Sam were raised in the hunting life by their father after the demon Azazel killed their mother. Dean's main role in the series is being the self-appointed guardian of Sam and often going to extreme lengths to protect him regardless of personal cost. Often in these occurrences, Dean finds himself the center of a much larger picture. When he was killed by Metatron whilst using the Mark of Cain, Dean returned as a demon and a Knight of Hell loyal only to himself. He was then cured by his brother using purified blood.