His family has an affinity for the paranormal, possibly because his ancestor, Frodo Bagans bore the Ring of Power
Something is wrong with Zak.
At first, the shows have a relatively lighthearted bent and focus on the investigations and insights on what happened at the locations in question. Fast forward to season 10, and you have Zak doing things that make his very team uncomfortable, experienced paranormal investigators who know what they're getting into. Zak seems to be taking larger and larger steps away from safety, which has already cost him one friend and possibly made certain locations worse. Whatever the cause is, until it is addressed things might get worse for the GA crew.