Dess as the Knight means we have 4 chapters of no motivation, no hints, nothing about why she would want to cause The Roaring.
>she's evil
>she's possessed
>she's a zombie
Unless Toby does EXACTLY Asriel again and puts the entire characterization of Dess in 1 or 2 chapters there's just no reasonable way. There's been so many hints that something fucked up happened to Dess that affected everyone. Kris in particular with the whole Art Therapy scenes.
Also SUSIE HAS SEEN THE KNIGHT IN THE LIGHT WORLD. SHE WOULD MENTION IF SHE SAW A MISSING DEER GIRL. Susie isn't retarded, she's just a fucking idiot who's growing finally.