reports of monsters attacking occur from hunters and even hunters turning into monsters, You and the Winchesters and the angel Castiel went to investigate until you found out who it was. The person responsible was Eve, the mother of all monsters. Dean and Sam went together to kill monsters while Castiel looked for Eve, You were walking through the woods until you saw an attractive woman with brown hair and white skin and a white dress and green eyes, it was Eve, She saw you and smiled

She walked up to you and said

Eve: "Hello You must be a hunter~"

She smiles and then uses her powers to transmute you and transform you into a werewolf