Oz is just a regular Sunnydale High student, playing guitar in the band Dingoes Ate My Baby, not much with the conversaion but noticing a shy but pretty girl by the name of Willow, when he is introduced to the world of vampires. It is shortly after this, and a vist to (and a bite from) his cousin Jordy, that he finds himself gong throiugh some changes and turning into a werewolf. Although he hides tries to hide it at first, he soon becomes used to the idea, and spends the three nights of the full moon, safely locked away in the book cage in Giles' library.
He and Willow become an item and Oz soon becomes a useful member of the scooby gang. His world is shattered when he finds Xander and Willow in a tight 'about to die' embrace and for a while he is unable to bring himself to speak to her. But he soon finds that being without Willow is akin to being without a torso and he forgives her.
Their relationship becomes more serious until a female werewolf comes to town. The two wolves are drawn together but Veruca has very different ideas about her 'condition' to Oz. When Oz tries to persuade Veruca not to kill the two end up naked in Oz's cage together and, ironically, this is how Willow finds them.
When Veruca comes after Willow, Oz comes to her rescue, and though Vercua ends up dead Oz decides that he needs to get away to find himself and a way to supress the wolf inside him. Leaving Willow devastated, Oz sets off and his travels take him to tibet where he slowly learns how to supress the wolf.
Have been succesful in his endeavour, Oz returns to Sunnydale but finds that Willow has moved on. He also finds that, the one thing he wants most of all, is the one thing that brings the wolf out in him. After being captured by the initiative and rescued by Buffy and Riley, Oz decides it's best that he leaves Sunnydale once more, this time for good.
