'Salem's Lot has lots of mystic forces pushing people this way and that. Some seem bad (vampires), and some good (the church), but none come into focus totally clearly. How is the Marsten House related to the vampires, exactly? Can you resist vampiric hypnosis or not?
The answers are slippery. It's hard to say whether this is because fate and free will are complicated, or if it's because the novel is more interested in effects than in fate or free will. The Marsten House is creepy because creepy is cool, right? And Mike Ryerson has to be hypnotized because you can't get Danny Glick out of the coffin otherwise. If 'Salem's Lot is fated for doom, that may be because Steven King knows that doom is what you expect from a horror novel.
Questions About Fate and Free Will
When characters like Dud Rodgers and Corey Bryant are turned into vampires, do they choose evil? Or not? How can you tell?
Does Danny Glick have free will when he does evil as a vampire? Does Sandy McDougall when she does evil before being a vampire? What's the difference, if there is any?
Are Susan and Ben fated to be together?
Chew on This
The town is taken over by vampires because its people choose evil freely.
The town's fate is to be always the same, and that sameness is symbolized by vampires.