Near the end of Dragon Keeper, Sedric Meldar takes scales and blood from the copper dragon, with the aim of selling them to the Duke of Chalced. However, he is strangely driven to drink some of the blood. He packs what he has stolen and mentally congratulates himself.
Sedric lies ill for several days after drinking the blood and the dragon's thoughts begin to intrude into his mind. She doesn't hate Sedric for taking her blood but instead is protective of him. He begins to change into an Elderling.
While Sedric is ill, so is the dragon. She is guarded by Mercor, who senses she may die. She nearly succumbs to parasites, and the keepers rescue her from an infestation of Rasp snakes. Mercor shares her name, Relpda, with the group, and watches over her while she heals.
After the massive flood takes them away from Tarman, Sedric and Relpda are dependent on each other to survive. When Jess tries to kill Relpda, Sedric fights him off, and Relpda eats the hunter. They are eventually found by Carson, who leads them back to the Tarman.
Later Relpda becomes distressed when Sedric tries to take his own life, and she warns Carson to save him in time. Relpda confesses that she knows Sedric took her blood, but she has forgiven him, and is happy for Sedric to be her keeper, and to help his change into an Elderling.