>>28479274The facial structure between the two is completely different. Just look at the mouths. Midday form has an actual canine snout, Midnight form has something like Lucario's weird mouth placement.
Besides, the obvious answer is that Midnight one is Rockruff "turned inside out". Its fur patterns are evocative of exposed muscle and it's literally wearing Rockruff's normal pelt on its back like some kind of skinwalker.
