Could The Event Sean Be A Sentinel?
On the last episode of The Event, Dempsey claimed he was a sentinel or guardian. From what he said I got the impression that a sentinel was supposed to guard the earth from other alien races from invading and taking over the planet like Sophia and her people are poised to do.
Dempsey was also curious why Sean had been able to overcome every obstacle that was sent his way, and there's been a lot of obstacles. He was framed for murder. He was accused of being a terrorist. Several hit squads have been sent after him to kill him and he's still alive.
A real clue to Sean being a sentinel was when he was feeling defeated and he was just going to go away. His sister said it wasn't like him to let someone get away with victimizing children the way Dempsey had been and to just run away. After that, Sean went on a mission to find Dempsey and stop him. That seems to be something a sentinel would do.
At present Sean doesn't seem to have a major part to play in this human vs. the sleepers thing. Yet Sean seems to have a bigger part to play in this than just being Leila's boyfriend. So perhaps he's supposed to replace Dempsey as the new sentinel.
Of course, we still don't know what it means to be a sentinel. We don't know why Dempsey has unearthed some ancient tome. Hopefully, this week's episode of The Event will shed some more light on it.