i was thinking it's him too, i was hesitant bcos it's narrated through his perspective and he doesn't seem to know anything at all other than what he already know pre-apocalypse. tho if it's between guwon and him, teach would make more sense. i also think I got too caught up with the title, especially "the hounds" and who owns them in right now.
lol but what if it's not a returnee story at all

theory 1: guwon is Sisyphus (implications: he's a returnee) and the hounds are, ofc, the hounds. but i also feel like that's too in the face. also he's kinda clueless and ig dumb, he's like all brawns no brain, which I feel like negates the sisyphus thing.
i really feel like this manhwa COULD potentially be a lot more intentional and well-planned than you would initially think. though, it would lowkey be sad for the author bcos their readers are all about the yaoiness and "psychoness" of guwon.