and that Eto thinks Kaneki her child. But the best way I can think to describe their relationship is with this quote:
Hades to Persephone “Go now, Persephone, to your dark-robed mother, go, and feel kindly in your heart towards me: be not so exceedingly cast down; for I shall be no unfitting husband for you among the deathless gods, that am own brother to father Zeus. 
So to determine if Kaneki (Persephone) will go with her mother (Eto = Demeter) or husband (Arima = Hades) in the upcoming arc, it will depend on if Persephone has been to the Underworld or not.
There are two possibility for what will represent the Underworld in TG: Cochlea or V
Cochlea is literally underground and contains the souls of the damned, but V headquarters looks like the dark palace that Persephone resided in. 
If Kaneki goes with Arima a la December 20th, most stories seem to agree that Persephone stays for 3-4 months before heading back to her mother once more (December 20th to April 2nd is about 3 and a half months). So a possible stay in Cochlea/V for a few months before heading out once more.
If this possibility happens, then the world outside will be miserable since Demeter wanders alone knowing her child is gone till the vegetation returns once more (and wrecking desolation and harshness wherever she goes)
So our dearest Persephone doesn’t know the cold she leaves behind when she goes off to meet her husband or mother (Everybody that loves Kaneki back in TG, and now the Quinx in :re)
Anyways, I’m never writing this much again (and maybe I’ll write more on Eto as Demeter on a later date)