Threnody is the crossbreed daughter of D. Metria and Gromden and wife of Jordan. She can shapeshift because she is part demon, but it takes her an hour each to get the aspects of the form, like appearance, size, and mass. Her talent to create a song which will drive people away.
She is the result of Metria "fooling around" with King Gromden, her father, so she is technically a princess, but her jealous stepmother cursed her so that whenever she entered Castle Roogna, the royal castle of Human-Ruled Xanth, it would fall. Because of this her father sent her away, but there was a second part of the curse: Once she was sent away, Gromden didn't remember the curse! So a few years after she was sent away, Gromden sent Jordan to go and fetch her, not telling him what he was fetching. Jordan eventually got her to the castle, but was killed by a final booby trap at the drawbridge.
Threnody made sure he could not come back by hacking his body into pieces. She buried those pieces in places so obvious no one would think of them being there, like his head under a skullery tree, his pelvis by a large ash tree, and one of his feet by a shoe tree.
Threnody had an unhappy life with King Yang, who she was set to marry because Jordan did not complete his journey. She committed suicide and became a ghost at Castle Roogna named Renee for 400 years. Jordan and Renee fell in love again. When Jordan was reanimated by Ivy, he had Threnody reanimated as well. However, when Jordan found out Renee was Threnody, he was seriously miffed.
Threnody and Metria did not have a cordial relationship. When Metria tried to serve the Simurgh's summons, Threnody kept running away and keeping Metria away with her talent. Only after Metria was able to reverse the curse, did the two women reconcile.