Bly Manor is very different from Hill House, so comparing the two does each a disservice. Bly Manor is a lot less reliant on using little-known or unknown ghosts to drive the plot forward. You won't find jump-scares here. This show is all about the horrors of human nature. Don't expect quick explanations of anything. Do expect to see lots of ramifications. It's all about the slow-burn here.
Bly addresses different themes overall: the heavy burden of guilt, the ways romantic and familial love help and harm, how loneliness warps the spirit, self-sacrifice, human willpower, coping (or not) with grief, loved one's abuse of trust, betrayal and how the consequences of others' actions irrevocably ripple outward.
Speaking of the slow-burn, there were breadcrumbs of foreshadowing dropped in the first few episodes that were picked up and addressed in later episodes. It all comes together in the end. The way the show was set up as a retelling of a ghost story was interesting.
The ensemble makes the show. You learn a lot about the characters, even the tertiary characters like Miles and Flora's parents. I really liked the deep dive into how Bly Manor became haunted, and how events centuries ago informed the present. I felt like I actually knew and understood most of the characters and their backgrounds, minus Jamie's brief explanation of her family situation.
Let's talk about the fashion. Oh my goodness. I love it all. Hannah's fondness for smart turtlenecks and chunky earrings. Dani's unconventional 80's pants and blouses, and her chemise nightgown. Miles' sweaters and sweater vests. Jamie's comfortable gardening attire. Owen's round, wire-rimmed spectacles. Rebecca's... Everything. Even the detestable Peter Quint looks like a stylish, attractive mistake you could maybe let yourself make just once.
Spoilers below.
Stop here.
This is your last warning.
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I think a lot of this show centers around how one person's flaws end up hurting innocents around them. Henry's missteps inadvertently sends his brother and his love to their doom. It also distances him from Flora and Miles, which allows the dangers in Bly Manor to envelope them. Peter's parents mistreated and used him, so he made poor choices to try to get ahead, which screwed him over, and he betrays Rebecca to try to get his way instead of letting her go. (Adult Peter is not an innocent, mind you. He's quite manipulative, abusive, and scary to watch. Peter as a child is innocent, and adult Rebecca is innocent.) Viola hurts Perdita, who then hurts Viola, who then again hurts Perdita, one last time. Dani doesn't mean to hurt Edmund in being honest with him, but she does. The drama between Jamie's parents and the culmination of the town gossip falls on Jamie.
The Willoughby sisters remind me of Cain and Abel. Viola's arc in the chest is so sad, how she was waiting to see her daughter one more time, but never did. To see such an ambitious, spirited, strong-willed woman trapped and then faded down into a sliver of her former self, it's crushing. Alternatively, it was interesting to see how a willful woman who didn't have much in the way of rights or ability to own property protected her inheritance in the 1700s.
Watch Bly Manor because it's interesting and layered, not because you want it to be another Hill House. Or watch it for the hidden ghosts. Your pick.