Etheldredda never went anywhere without the Aie-Aie, which she had had since she was a young girl. She had found it in her garden when it had fled from a ship. The Aie-Aie could give people the Sicknesse when it bit them. Queen Etheldredda was the last to wear the original Queen's crown, but it fell down to the bottom of the moat when Etheldredda drowned and it remained there until Jenna Heap got it.
It was revealed that she tried to become immortal, partially unsuccesful, by drinking her son Marcellus Pye's Tincture for immortality. The potion that she drank was not ready yet and she became a semi-physical ghost, known as a Substantial Spirit. She killed her two youngest daughters and tried to kill her eldest one once the potion was nearly finished. After she was liberated from the attic by Silas Heap while searching for a room to secretly house a colony for his game, Counter-Feet. She was later intent on killing her heir, Princess Jenna. She was finally ended when her portrait was burned by dragon Fyre. Her pet Aie-Aie also drank the unfinished Tincture and was also sealed along with its master.
Queen Etheldredda is described as being a scary looking woman, with her grey hair pulled into two coils and violet eyes with a very pointy chin. She wore a high ruffled collar and a dress that was fashionable 500 years ago.