thank youuu it's a little indulgent and crazy so hear me out hahahaha.

etheirys is a different realm, similar to the lands between. in elden ring it's implied there are other lands after all. venat is a goddess much as marika is, then, just of this land. sveinn is a demigod empyrean, akin to miquella or malenia. he was a contact of miquella's, penpals if you will. they lost touch during the shattering.

zenos is a tarnished who never went to the lands between and died. he only came to them when marika called them back (so for elden ring) but he only cares to fight, not progress msq.

sveinn came to the lands between to learn of what happened to the demigods, because the news of the shattering didn't reach realms outside the lands between. he however, wants to avoid interfering too much, he's worried about upsetting a balance.

zenos lacks a maiden (scared her off), he meets sveinn on a coastline in limgrave. he learns sveinn is a demigod, but a fully lucid one, who is reknown for combat. sveinn tells zenos he will play the role of his maiden and help him turn runes to strength, if zenos acts as his conduit to explore the lands between and learn what happened around here properly. there's no real end to the story, but sveinn mostly plays a support role to zenos, being unwilling to fight anyone himself (it was against venat's rules for him to fight other deities when he left).

i think zenos will fall in love with sveinn and choose not to become a lord though. whether he goes to sveinns home with him, or whether he dies i'm unsure. i'm not deeply invested in it as a story with an end haha.