Later, we learn through psychiatrist appointments that the girls’ captor is Kevin, a young man with a past filled with childhood trauma that is the root for his Dissociative Identity Disorder (previously known as multiple personality disorder). Kevin has 23 different identities, with the dominant identity being Barry; however, recently other “repressed” identities have been taking him over. The girls meet these repressed identities, including Dennis, Miss Patricia, and 9-year-old Hedwig, all of whom tell the girls that they are special food for “The Beast,” a mysterious previously unknown 24th identity.
Overall, the film is ripe with instances of style for style’s sake, and its story feels very clunky: Casey has several intermittent flashbacks, revealing her to also have sustained serious childhood trauma and have learned how to hunt wild game, a skill that comes in handy in her current situation. Meanwhile, the other two girls attempt a few harried escapes only to be quickly foiled, while Casey takes a more cautious approach. The captive/escape plot is unsurprising and familiar. Cliché and heavy reliance on unnecessary exposition undermine any real sense of suspense. The ‘mental illness as horrific’ trope is initially uninteresting and uncomfortable, and the story is heavy-handed and prescriptive, hinging upon Kevin’s psychiatrist’s, Dr. Fletcher’s (Betty Buckley), belief that people with DID can, somewhat supernaturally, change completely in physicality with each different identity- a literal manifestation of mind over matter. Moreover, most of the characters are superficial and boring. The captives, aside from Casey, are given no depth, acting purely as means of raising the stakes for Casey’s escape.
McAvoy’s performance, however, lifted the entire film. He was excellent, truly selling the character and making each identity special and believable, even occasionally transforming between identities from line to line, his entire face seeming to shift in structure. The audience spends quite a bit of time with Kevin, getting a tiny window into his perspective and world. Each of his personas are more interesting than any other character; in fact, I was somewhat disappointed that we don’t meet more of the 23.
There are a couple of good twists in the film (Shyamalan does have a reputation to uphold, after all). The first one is good and truly surprising, while the last major twist serves as just another schlocky way to further hammer in the aforementioned message and mask an otherwise dull ending. All of this leaves Split having the ingredients for a thought-provoking horror flick or psychological thriller, but never quite gelling into something great.