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If you can't stop thinking about the teaser trailer of The Haunting of Bly Manor, we'll give you a few details to think about 
1 - There's something really creepy about The Lady of The Lake's eyes.
2 - Dani is locked in Flora's closet, apparently screaming 'Let me out!'. However right before this shot, we see that there's no one outside the closet -- she's screaming to a empty room. The Wingrave children pranking their new nanny or Peter Quint's doing?
3 - Something happened at the church.
Actor Jim Piddock plays a character called 'Father Stack' this season. While we still wait to see this Father, seems like something bad happened at the church where he acts, cause Jamie gets an alarming call and visits the place with Dani. Why would they need the weapons?
4 - Rebecca Jessel's tragic storyline in three acts.
5 - The doll right in beginning of the teaser trailer reminds a lot The Lady of The Lake.
While some of Flora's handmade dolls have eyes, a nose and a mouth like the one made for Miss Jessel, this one in the basement doesn't seem to have the same features. As aforementioned in this thread, looks like the Lady of the Lake does not have eyes.
So technically, the teaser shows us two encounters between Dani and the Lady of the Lake (this doesn't mean anything I am just bored and I can't sleep).
