So I'm piggybacking off of what Kab wrote about our beastmaster archetropes because what I think is probably a little closer to the body is the beastmaster/tamer and we are the beasts/mons. Most headmates in here could count as a monster or beast whether literally or metaphorically, and it's very common for headmates who don't technically fit to have a more mon-like representation (e.x. a Pokemon Trainer fictive in here has a pokesona he uses for himself more).
But when fronting it becomes a little closer to feeling like the body is the Beastmaster and we're being summoned, and with that we sort of become the Beastmaster as well as the summon monster. Though the body isn't really a thinking entity (unless you could Mebbit which... actually, wait a minute...)