The Carian family where originally astrologers, who preceded the sorcerers, establishing themselves in the northern mountains at the tallest peaks that nearly touched the sky, where the currents of glintstone are so strong they can be seen as floating shards in the air itself. Out of the house of Carian came a young sorceress by the name of Renalla, who bewitched Raya Lucaria with her enchanting magic of the full moon. She quickly rose the ranks of the academy, became the leader of the glintstone knights, and established the house of Caria as royalty. Eventually she earned the position of leader of Raya Lucaria, and queen of the full moon. She wed to Radragon, a peerless warrior from a foreign land. Under her tutelage, Radragon learned about sorceries from the greatest teacher in the lands between.
Renalla had three children, three princesses, these are likely the offspring of both Renalla and Radragon. Of the three only one remains to this day, Ranni the witch. The fate of the rest is unknown at this time. After a while though, Radragon left Queen Renalla and wed Queen Marika, joining both the house of the Moon and the house of the Tree. Renalla's heart was broken. Radragon's motives are still not clear, but it is known that he learned about incantations from Queen Marika, perhaps his only purpose was to become an even stronger warrior, learning both incantations and sorceries from the greatest teachers in the lands between.
Radragon gave as a gift an amber egg from the Erdtree to Renalla, who now spends all her days locked up in the library cradling the egg. Soon those at the academy noticed Renalla was no hero, nor leader that they thought. The egg is known to rebirth and create ephemeral, imperfect beings, but its full powers are still not clear.
Ranni the witch stole the rune of death, causing the night of the black knives, the fall of the demigods, which cascaded into the Shattering war. This rune gives her control over death, which is somehow connected to the amber egg(as seen during the Renalla boss fight).
Ranni's motivations are still a mystery, but she is searching for the "Darkpath" and wants to "rid the world of all that came before."
Ranni seems to be spiteful towards something, is it the loss of her sisters, or is it for Radragon marrying Queen Marika. Radragon gifting the egg shows that he still holds Renalla dear, and might be the ultimate motive of the re-marriage.
Why did Ranni steal the rune of death, what happened to her sisters? Is Renalla trying to resurrect her dead daughters? Lots of question yet remain to be answered.