5. A Truly Frightening Villain
The series' Big Bad will come in many forms and go by many names, but each and every iteration is frightening. And just when you think you've caught a break, the Big Bad will find a way to come back even scarier and more powerful. Think something akin to Loki, in that the villain is manipulative and conniving. But this one is so much worse in what it is capable of doing and its single-minded drive to acquire the keys and bring its demonic plans to fruition. A brilliant stroke employed by the creators is keeping this villain in frighteningly close proximity to the Locke kids. Yup, this villain takes the form of one of their friends, and we're stuck in that state where we want them to discover how evil this person they trust is, and we can do nothing but watch and hope. It's chilling to watch how easily the Big Bad changes forms, inserts into groups,friendships, and relationships. And there's a cold-bloodedness to the actions that is sometimes difficult to look at. The heights of evil which we are forced to watch, whether it's in the overt grisly actions, or the scheming, coercing, and manipulating, is sometimes almost unbearable. And also part of what makes this such amazing reading.