The ending of Netflix's Haunting of Hill House wrapped up the Crain family's story quite nicely, but is it possible that the ending is really just a continuation of Luke's dream inside the Red Room? Based on the novel of the same name by Shirley Jackson, Netflix's 10-episode limited series, The Haunting of Hill House, was adapted by horror filmmaker Mike Flanagan and starred the likes of Michiel Huisman, Carla Gugino, and Timothy Hutton, among several more, as the members of the Crain family.
The Haunting of Hill House TV show started off with Nell Crain's sudden death inside Hill House in episode 1, and it concluded with the rest of her family confronting the forces (and ghosts) inside the house's Red Room. While in there, every one of the Crain siblings - starting with Luke Crain - were presented with a dream that they had to overcome and escape from. What's interesting is that, in each dream, something in the vision is red, according to one of the stars. Taking that tidbit into account, it's possible that Haunting of Hill House's ending is much darker.
In the Haunting of Hill House season finale, the Crain siblings manage to escape Hill House (after their father willingly sacrifices himself), and then the story picks up and ends two years later; all the siblings are together again, celebrating the two-year anniversary of Luke being drug-free. However, in keeping with the idea that each dream in the Red Room has something prominent that's red in it, upon closer inspection, the Haunting of Hill House's ending may not be as happy as audiences realize.
In that particular scene, Luke's two-year anniversary cake is almost completely red. Since it's the central object in that room, it's theoretically possible that Luke is still stuck in his dream and that the rest of his family - including his father - weren't able to rescue him from the Red Room. It would make sense from the perspective that the Red Room has won and thus given Luke exactly what he's wanted: to be addiction-free and with his family again. Furthermore, the entire story of Haunting of Hill House has been primarily centered on the mother's (and the house, for that matter) relationship with the twins: Nell and Luke Crain.
It's a truly haunting idea to consider that Hill House took Nell Crain (the youngest twin) at the start of the series and then took Luke Crain (the older twin) at the end. Unfortunately, this most likely isn't something that will be confirmed or denied by the creative team behind the show, but it's yet another aspect of Haunting of Hill House to discuss as more and more people continue to check out the series on Netflix.