okay so. so eleos and philotes.
for context. they're part of a larger renegade warband/squad/whatever they feel like calling it that day. the starcrawlers. basically all various sons of traitor primarchs who have been tossed through time and the warp to 40k (something that we do see happens canonically within the Son of the Forest book with the destroyer Zabriel), who aren't loyal to their primarchs anymore but will Not be joining the imperium of man.
eleos is a world eater, one of those who implanted the nails upon angron taking lead of the legion. he inherited some of papa's empathy stuff he's got going on. he is also the group's only apothecary.
philotes, on the other hand, is a word bearer. he was a chaplain. once. he isn't sure what he is now, exactly, but he does act as a chaplain-esque figure for them all. one with questionable advice, but still!
as for the two of them, it's.. complicated. i think they've been together for a very long time, having been picked up by the starcrawlers together. they're a pair. you don't get one without the other. there's no privacy between them. they share a bunk on the ship the group's stolen because it eases both of them. they've kissed a few times. maybe. neither of them will really say, nor will they talk about any sort of feelings that may or may not be there.
over some time and with observations he's made, philotes is of the belief (and practice) that if eleos has something to focus on, if eleos has something to heal, then it helps him stave off the bite of the nails. but they avoid most encounters, so very rarely are any of them injured to the point of eleos actually having anything significant to heal.
so philotes improvises. comes up with ways to keep eleos busy, keep the nails at bay. all it costs him is a few broken bones from borrowing their iron warrior's forging hammer, a few more scars from where the stolen dagger from one of their emperor's children cuts open his flesh. a small price to pay for eleos. but the cost keeps escalating, and soon he'll have to start disembowling himself to even draw his eye.
on the other hand, eleos is soothed by philotes. his hymns and mantras keep him company even under the threat of bloodlust, the smooth hands of a former holy man soothe the irritated skin around the nails with gentle ministrations. philotes keeps him focused. keeps him on track. he fights the gnawing teeth for all of their sakes, given that he does care about them, but mostly for philotes.
they're definitely co-dependent on each other to an unhealthy degree, but i will say i think philotes is more dependent on eleos. not physically or emotionally, necessarily, but in terms of just having a purpose.
where eleos goes, philotes goes. it could be down a market street or into hell itself. when death takes eleos, if he has not been taken first, then you can bet your ass philotes will be following him into the afterlife with a bloodied dagger at his throat.
ending this off with what i said before about khârn and argel tal ran so these two could limp with their legs tied together like a 3 legged race
anyway. yeah. those are my guys