WARNING: The following contains spoilers for Locke & Key Season 2, now streaming on Netflix.
Locke & Key made its second season debut on Netflix by picking up the loose ends of Season 1, but it also builds upon the history of Keyhouse and the Locke family. That is further explored with introduction of Josh Bennett, the new history teacher at Matheson Academy, played by Brendan Hines.
At first, it appears as though Josh is being set up as a love interest for Nina Locke (Darby Stanchfield), the mother of Tyler, Kinsey and Bode, who, frankly, doesn't otherwise have much to do. After all, they share a lot in common: They were both recently widowed through tragic circumstances -- Rendell Locke was murdered and Josh's wife died in a car accident -- and decided to move their children to Matheson, Massachusetts; Josh teaches history and Nina restores old buildings; and their families have deep roots in Matheson, which could be a source of future conflict between them.
At the opening of Season 2, viewers are introduced to Josh's ancestor, Frederick Gideon (Kevin Durand), who served in the British army during the American Revolution. He harassed the Lockes in a way that resulted in casualties on both sides, eventually forcing Gideon and his men to retreat, and then stumble upon the Drowning Caves, where they discovered the portal to the demonic dimension. When the Lockes followed them inside to resume their fight, Gideon saw firsthand what happened to people who were shot with the Whispering Iron. Seeing it as a source of power, he allowed himself to be wounded by Whispering Iron before getting captured and subsequently executed by American militia.
Gideon's backstory has significant implications that could set Josh on a villainous path in Season 3. As a descendant of Gideon, Josh has in his possession his ancestor's diary and the piece of Whispering Iron from the Drowning Caves. Throughout Season 2, Josh demonstrates a single-minded interest in his family history, and especially their connection to the Locke family (he even purchased a dollhouse replica of Keyhouse). He obsessively pores over Gideon's journal and attempts to piece together a piece of his own history. Not being able to make sense of the other-dimensional portal Gideon describes in his journal, Josh grows increasingly frustrated with his research until Eden (now possessed by a demon in the Season 1 finale) offers to lead him to the Black Door.
When Josh is brought to the Drowning Caves, he is attacked by Dodge (posing as Gabe), who summons shadow demons to attack both him and Eden. Josh barely escapes the cave, and then only with the help of his daughter, Jamie, and Bode Locke, the latter of whom uses the Hercules Key. Like the other adults in Matheson, Josh is unable to remember magic, and rationalizes the accident as a hiking trip with his daughter gone awry. That seemingly convinced Josh to abandon his mission to unearth his family history, saying he only used it as a way to cope with his wife's death.
Although Josh chooses to let go of his grief to focus his energy on pursuing a relationship with Nina, Eden's resurrection of Gideon as an echo in the finale seems to suggest Josh's family history is not yet done with him. While Josh himself may not be loyal to the British Empire and may not possess the hatred Gideon had for the Lockes, there is still evidence of Gideon's villainous traits within him. The most obvious one is his temperament. When Gabe steals his piece of Whispering Iron (which, to Josh, is a family artifact) to craft a magic key, Josh becomes violently angry to the point of threatening two students for pulling a prank on him.
Josh's violent temper may also hint at something else about him that could play out in Season 3. Depending on when Gideon had children prior to his capture and subsequent execution, there's a good chance the Whispering Iron he took into his body could be embedded in his DNA. If true, this could further build on a concept that was started by Gabe in Season 2. Because Gabe crafted a key that could turn ordinary people into demonic entities, this established that demonic possession doesn't necessarily require taking in a piece of Wjispering Iron. Exposure to its properties alone seem to suffice.
In a case where the Whispering Iron's properties are passed down genetically, this could easily expose Josh to falling victim to an echo's control. With his ancestor now running loose as an echo thanks to Eden, Josh could very easily be forced to join forces with his ancestor, whether he wants to or not. This alone could put him at odds with the Lockes in Season 3 and could easily shake up his budding relationship with Nina.