Ranni lore/propaganda because there is not enough support for the swaggiest lunar princess
The doll body that we see in-game is of her own design; she was once an Empyrean (demigod and heir to the throne of the Lands Between), but hated the restrictions imposed on her by such a role. To free herself, she had her stepbrother Godwyn's soul killed with one half of the god-slaying Rune of Death, while she destroyed her own body with the other. Ranni transferred her soul to the four-armed doll, modeled after a snow witch who served as her mentor in the past, while unlucky Godwyn lies as a soulless, fishlike husk in the Deeproot Depths. What I'm saying with this is that she has morally ambiguous transgender swag.
She can be married as part of her questline (regardless of your character's gender), which unlocks an ending where your character becomes her consort and she begins the Age of Stars, an era governed by a new order distanced from the Golden Order that ruled before her.
Her questline involves two other characters - Blaidd, a brave, amicable half-wolf warrior, and Iji, a gentle old giant who serves as Ranni's war counselor and a blacksmith. They're both very nice fellows and I love them.
Also, there's a song about her, and it's absolutely amazing.