We don’t actually get a whole lot of info about Casey, except for her past of sexual abuse and quick thinking. But Michelle begins the movie fleeing abuse, and due to her very real arc by the end (something lacking in Casey), she is able to stand up to her abuser. Split’s message of “abuse is basically good” really makes no sense, and the movie ITSELF has no payoff...although that last “twist” is clever (kinda), if a bit tacked on. 10 Cloverfield Lane is not perfect either, and the movie would probably have been better off without the aliens. The superior theme/conclusion is 10 Cloverfield Lane. Both movies have great tension at times, but 10 Cloverfield Lane has better tension.