Ben 10: 3x5

Benwolf

Ben, as Wildvine, is fighting against an evil werewolf and is bitten. The Omnitrix times out and Ben turns back to his human form. Then, when the werewolf hits the Omnitrix, it starts to mess up and act weird. After all of this, Ben starts to get a crush on a girl that he meets. But things change, as Ben slowly starts to turn into a werewolf himself.