Seraphine and Illaoi would have an interesting dynamic.

Illaoi and her people worship Nagakeborous, who is in part a god of motion and the waves. Seraphine uses a different kind of waves to put people in motion.

Sure, the whole ritualistic violence and cosmic tentacle horror would scare the crap out of Seraphine, but I have no doubt that she'd pass Illaoi's test of will. Meanwhile I also have no doubt that Illaoi would be the best dancer in the crowd at Seraphine's concert.

They'd probably learn to appreciate each other, in a way, despite their differences. I hope that they'll get to interact with each other in the lore someday.