Karen was switched to the other "demention" during a solar eclipse where 3 people hold each others hand and say things (We're looking to you, Karen Alywood etc). The watcher told this to Jan & Mrs Aylwood by taking control over Ellie's body and writing things down during that last night.
He needed Jan to convince John Keller, Tom Colley and Mary Flemming. I think that's the reason why he saved Ellie from being hit by the truck and Jan by the motorcycle. He knew they were "the chosen" to bring him back to his own world.
The Watcher could leave the wood, but he wanted to return to his own world and knew the only way to return is when the same people hold each others hands during a total solar eclipse (That's why he left all those messages and signs for Jen).
I also think Mrs Aylwood knew Jan would be the perfect person to find out what happened to her daughter.
"She's going to stay here... is that what you wanted?"
Mrs Aylwood stalked Jan since the beginning of the movie. The best example for this is when she fell in the water. Mrs Aylwood was immediately there to safe her life.
The Watcher planned this before he actually saw the family Curtis. The old lady you see in the beginning driving the car called Mrs Aylwood, even though Mrs Aylwood never answered the phone. It's obvious the Watcher prevented this, because Mrs Aylwood is not the most friendly individual you can imagine and either the family Curtis or Mrs Aylwood would refuse to stay there.
"Shame on you if you fool me once, Shame on me if you fool me twice
reply
share