Mostly though I do think it was just JM doing his thing of yanking the audience completely off-balance. When our comfy reliance on well-known actors always being the star (or the murderer) makes us complacent that we can always second guess any writer, blithely offing your co-lead at the series midpoint does rip up the jaded TV audience expectations book, just a bit. In the end far to sweet for a closing episode.