I was thinking of maybe having her wander off alone when Caius is out scouting. She comes across a rogue wolf and gets bitten. But said wolf has no intention of turning her, it merely wants to act on its rage and tear her apart. But -insert hero song here- before it can actually do that, Caius comes to the rescue and kills off the assailant wolf. BUT although she wasn't killed, the damage has been done, Callie will turn in the next full moon.