okay now thinking of spinning this into a bigger setting
so the idea is that some time in 21stC a bunch of tetraspaces come to earth just living their normal tetraspace lives which causes problems because tetraspaces are cosmic reality warpers
comes to a head in the Malchasis Disaster, where a tetraspace fight in the upper atmosphere spreads a cloud of radiation over much of a continent. objectively not all that bad, but spooky radiation, and more tetraspaces come to earth each year
occasionally tetraspaces grab humans and take them on exciting cosmic adventures. most of what people know about tetraspaces comes from these humans, and it comes to light that the lives of tetraspaces are brutal and precarious and that if one was able to lay their eggs on earth
in this setting you can enthrall a tetraspace to do your bidding by giving them/it headpats (not magical they just like headpats). but this is hard to discover because these tetraspaces burn to the touch
now that ive been reading twig and also replaying hello charlotte and also just thinking more about the logical consequences of the setting obviously there should be body horror tetraspaces
so the reason tetraspaces adopt human forms is to communicate with humans. "their" "goal" is to find the strongest million or so humans, implant them with tetraspace eggs, they fight to the death, the ~1% who survive get to be the new tetraspaces, repeat
of the remainder, some just don't get humans quite right. facial features are off, "close enough" by their standards but not by ours. arms and fingers the wrong length. garments don't actually make sense as clothes if you pay attention.
some have strange aesthetic preferences by human standards that they incorporate into their human forms. tetraspace likes ribbons, so a tetraspace might decide to have two mouths with six tongues each about a meter long trailing behind them, stuff like that.
some make the reasonable inference that humans probably have repeated body parts folded into four dimensions that they hotswap and do the same for their human forms and just have too many arms and fingers and eyes and stuff that keep flickering
some take sliders vaguely correlated with human attraction and slide them up really really high, past the superhuman range and just keep going. cheekbones high enough to be horns, giraffe-necks, bug-eyes, stuff like that
(humans of course make similarly egregious mistakes about tetraspaces. most of them can't even sight-read clan membership! that's like seconds-to-get-it-right-life-or-death info they're totally blind to!)