Like all Claymores, Priscilla had blond hair and silver eyes, though both were brown when she was human. Among Claymores, she was relatively short, standing at 165 cm. She appeared to be in her mid-teens and wore the standard warrior uniform.
As an Awakened Being, her appearance is significantly altered. She appears as a winged humanoid about 2 m tall with a single horn on her forehead, rather like a Japanese oni. Her hair is similar to the way it was in her Claymore form, but more tousled than usual, and she retains much of her human face with the exception of her horn. In the anime, her skin is a light shade of blue-violet.
Priscilla's personality goes through several phases. At first, she was childlike and emotionally distraught from seeing a Yoma kill her family. She saw everything as being black and white and viewed Teresa as evil for killing humans. When she lost control of her Yoki and began to Awaken, Priscilla begged Teresa to kill her.
After Awakening, Priscilla displayed an aloof, sadistic personality, finding Awakening to be a pleasurable experience and immediately craving human flesh. However, her mental state began deteriorating and after her fight with Isley, she lost her memories, her mind reverting to that of a child. Over time, she formed a bond with Raki due to the lingering scent of Teresa through Clare. While travelling with him, Priscilla slowly regained her memories, though she continued to play the part of a child to manipulate him, starving herself to the point where her body degenerated. After the Destroyer's attack, Priscilla restores her body by gorging herself and reveals her deception to Raki. Despite imbedding her arm in his back to suppress the Destroyer's parasitic rods, Priscilla later claims she felt nothing towards him and spared his life on a whim.
After regaining her memories, Priscilla became intelligent and very arrogant due to her power. While fighting Dauf, Priscilla finally remembered Teresa's death, though she continued to suppress other memories related to her childhood. In her pursuit of Teresa's "second death," Priscilla set out to kill Clare, whom she called a child.
After Clare and Raki supposedly finish her off, Priscilla returns in a deranged and maniacal state. Presumably due to most of her body being destroyed earlier, her mind reverts to a primitive need and hunger for flesh in order to reconstitute her form. In this state, she views everyone that she encounters - including humans, Claymore warriors, and other Awakened Beings - as just sustenance, and has no problem in attempting to kill Raki, whom she used to share a bond with.
It is ultimately revealed that before being suppressed by her Awakened Being persona, Priscilla's human self installed a psychic wedge to prevent herself from attacking young girls in the hopes they would become Claymores powerful enough to kill her. Priscilla's lust for battle and desire to fight Teresa again were subconsciously driven by the remnants of her human self's desire to find an opponent strong enough to kill her, something her Awakened Being persona didn't consciously realize. In her Awakened state, Priscilla was condescending towards her human self, as revealed during her conversation with Dae. She was oblivious to the psychic wedge the remnants of her human persona installed until informed of it by Dae; and during her fight with Riful's daughter she remarked she stabbed herself with her sword on a whim because she didn't feel like parting with it, whereas when Priscilla's original human persona asserted herself she reveals it was an attempt to kill herself. Priscilla's human self apologizes for the suffering she caused, thanking Teresa for putting her out of her misery.