User blog comment:ND999/Daemons of Runeterra/@comment-4664737-20150711032947

Frankly, if you ask me, Riot is trying too damn hard that it's becoming more tedious and unclear of what they're trying to convey and most of it got lost somewhere in the translation. I get that they're trying to set up their own nest just the way Blizzard has had with their franchises but the main difference from the two is that Blizzard stuck to what they had rather than scrape it clean and restart like the Great Lore Disaster of 2014. They should've just stood their ground with what they started and make the most out of it.

Anyhoo, I'd rather think that Riot is going with the Warhammer40k's The Warp with their current direction. That demons are a manifestation of the combined darkness in the hearts of mortals as a whole instead of as a separate species. Either they were brought to existence of a power we don't know as of yet or magic or that they existed way before that and merely took the mantle of a chosen sin as their personal domain.

Of all the demons you've mentioned, Beatrice seems to be the most appropriate and very fitting for it. Brand can be easily dismissed as an Elemental. The rest have potential but I don't buy it.