Having your sim explore the (rabbit holes) hidden location, I think they are tunnels or caves, forget at the moment. They can have werewolf encounters. If they are already a wolf, it will be a pleasant experience, but if they are not, their encounter might leave them with a werewolf bite that can progress into the sim turning into a werewolf.
Once I had a sim who was attacked and bitten by Greg. That very night was a full moon, my sim became a werewolf that night. Normally you have 3 nights to cure them if you don't want your sim to become a wolf.
Besides the attitude, werewolves can be quite fun to play. With the right perks, they won't even need to live in a home. Meaning they can clean themselves (no bath), mark territory (pee outside), sleep on the ground, and hunt for their food.