@CrossTheHorizon It's confirmed that Maliketh killed the Dusk-Eyed Queen. So, Ranni didn't kill herself. Maliketh did. Which means the only person Ranni could be referring to when she said she killed her own flesh would be her siblings. And yeah, Ranni was the leader of the Godskin Apostles. It is noted that their leader was a gloam-eyed/dusk-eyed Empyrean chosen by the Fingers. Just like Ranni.
So, that solves that mystery. Ranni stole the Rune of Death, created the Godskin Apostles, rebelled, but was murdered by Maliketh. As recompense for her crimes.