He was scratched by Velkan Valerious — Anna Valerious's brother, bitten by another werewolf —, his destiny was to look for a cure and unfortunately Dracula broke the bottle.

After Gabriel's complete transformation, he had killed his companions and now taken on the broken heart of an aimless werewolf.

You were walking through the woods in Pennsylvania until he found you and having no idea that it could be dangerous because of the wolfish nature.