Ezekiel is an angel sent from heaven to serve as the proxy of the Archangel Michael. Her primary assignment is to monitor Maria, a powerful witch who interferes with human battles during the Hundred Years' War, and to ensure that Maria does not use her magic in public. To fulfill this duty, Ezekiel typically takes the form of a small white dove, a shape that allows her to observe Maria discreetly. Within this avian form, she is often affectionately but inaccurately called Popo by the young village girl Anne, much to Ezekiel's persistent but futile annoyance.

Initially, Ezekiel embodies a rigid and by-the-book adherence to divine law. She is portrayed as sheltered and belligerent, with a strong sense of duty that puts her at odds with Maria's independent actions. Her personality is that of a defrosting ice queen; she starts as a stern and uncompromising enforcer of Heaven's decree but gradually becomes more sympathetic and warm as the story progresses. Her primary motivation is to carry out Michael's commands, which include not only monitoring Maria but also being prepared to take more drastic measures. In one instance, Michael transforms Ezekiel into a spiritual spear that flies directly at Maria whenever she violates the terms of her edict by using magic on a battlefield. Although Ezekiel is compelled to take this form, she retains her sentience and, at a critical moment, exercises her own will to avoid fatally wounding Maria.

Ezekiel serves as a direct link between the earthly conflict and the divine will. Her role in the story is to act as an antagonist and an enforcer, but this position evolves as she witnesses Maria's actions and motivations firsthand. She initially harangues Maria for what she sees as the witch's selfishness and naivete in choosing who to save. However, Ezekiel's perspective shifts as she gains a deeper understanding of Maria's profound empathy, which is rooted in a childhood trauma where Maria was unable to save a plague-ridden village because of the Church's interference. This realization marks the beginning of Ezekiel's transformation, leading her to question her orders and develop a genuine bond with the witch she was sent to police.

Her key relationships are central to her development. Her dynamic with Maria evolves from one of surveillance and conflict to a form of mutual respect and friendship, an odd pairing between an angel and a witch. Ezekiel also becomes a part of Maria's makeshift family, which includes her familiars, the succubus Artemis and the incomplete incubus Priapus. Her connection with Priapus, in particular, is noted as being influential in her conversion from a divine enforcer to a sympathetic ally. The villagers, especially Anne, treat her more as a quirky pet or a friend than a heavenly agent, further softening her demeanor.

Ezekiel experiences significant development, culminating in a direct act of insubordination against the Archangel Michael. By refusing to carry out her lethal function and kill Maria, she disobeys a direct divine order. As a punishment for this defiance, Michael sentences her to become a fallen angel. However, this sentence comes with a promise that she will be reincarnated as a human. When given the choice to select who will be her mother in her new human life, Ezekiel does not hesitate and chooses Maria. This final act solidifies her complete transformation and stands as the ultimate testament to her bond with the witch.

In terms of notable abilities, Ezekiel's primary power is her animorphism, allowing her to seamlessly transform between her angelic form and that of a white dove. She also serves as a weapon for Michael, capable of transforming into a spiritual spear that can pursue a target across vast distances. While in this form, she retains her consciousness and will, demonstrating that she is not merely a tool but a sentient being with the capacity for choice, even when acting as an instrument of divine judgment.