I can't find anything on a Seleos in mythology at the era of that of "Enki" (no that I know as much I'd like about the religion and political going ons of that era anyway) . Is Seleos that name a mashup of Eleos and Celeus, from later Greece? If it was only the name of a created character, then no matter. (Still, the "sele" part does make me think of the moon and of some books with a sandman.)
The plot turned out kind of how I had expected it given the initial settings, and this very rarely happens in visual novels: usually otome girls are so trusting and can barely remember their names before any sprite (the character picture, I mean) that looks good at first glance. And since this game somehow looks like an otome, it's insightful. In that way the plot was weirdly realistic: the idea of accepting a powerful, and disconected and rude creature certainly couldn't end well). So realism about that was a welcome surprise. But it also feel like the plot express an opinion from the author, or someone around of the author. There is a uch deeper story, or an amount of story pieces around of that story.