Poor Derek. In Teen Wolf Season 3, Episode 10, "The Overlooked," the werewolf gets more bad news. Jennifer Blake, the English teacher he's grown very fond of (and gotten very naked with) is actually the darach, the druid who's been killing lots of people. The breakup will be a little messier than usual because she's the only one who can help his sister, Cora. Despite her werewolf healing powers, Cora is in the hospital with some life-threatening symptoms. The Alpha pack is keen to kill Jennifer, so she needs Derek's protection. Just when Derek's heart had learned to love again.