Us ending explained (spoilers)

[discussimdb]

Peele has explained his take on this twist ending:

This movie’s about maybe the monster is you. It’s about us, looking at ourselves as individuals and as a group. The protagonist in the movie is the surrogate for the audience, so it felt like at the end of the day, I wasn’t doing my core theme any justice if I wasn’t revealing that we have been the bad guy in this movie. We’ve been following the villain. I say 'villain' lightly because I think there are many experiences of the film, and I think a lot of people go through a question of what is good and evil? Does that even exist? Both characters are lovable and terrifying, based on the lives they’ve led they’ve just sort of inverted the paths.

That description really is a clear way of fitting this ending with the overall theme of the film. But what about that look between her and Jason?

Adelaide and Jason sharing that moment at the end, I’m purposefully leaving it a bit vague as to what exactly he knows or how far he’s come in figuring out what, if anything, he’s figured out. I think the little smile she gives him is a lot of things. I think it’s a connection to the evil smile she once had as a little girl, but also a sort of understanding that her family unit was stronger from this experience.