The character often referred to as Coatl in Miss Kobayashi's Dragon Maid is more properly known as Quetzalcoatl, though she frequently goes by the nickname Lucoa among her friends. In the world of the series, she is not a dragon but rather a former deity, specifically an ancient Aztec or Mesoamerican god who has since fallen from that divine status. Her background is explored when she explains that she now lives with a human family, which is unusual as it is a clan of magicians. She first appeared to the young son of this family during a ceremony in which he was attempting to summon a demon. To prevent a real demon from entering the world, Coatl appeared in his place, though her intervention has left the boy with a complex mixture of fear and admiration toward her.

Despite her divine origins, Coatl possesses a remarkably easygoing and laid-back personality. She exhibits a legendary confidence, approaching situations with a great deal of humor and a touch of audacity as she attempts to navigate her relationships with humans and other mythical beings. She has a strong nurturing and protective side, which is a common characteristic of beings with her name, and she seems to enjoy looking after others. Her personality contrasts sharply with the more serious or hot-headed dragons like Tohru, as she often seems relaxed and unfazed by the chaos that can erupt around her. A notable aspect of her appearance is that most of her on-screen moments show her with her eyes closed; she only opens them on rare occasions. Her dragon form is also a point of interest; during the first season of the anime, it was never fully shown and was only seen as a silhouette because the design had not been finished at that time.

Coatl's motivations primarily revolve around establishing a peaceful and enjoyable life in the human world. She seems to have a particular desire to make amends with the young magician who summoned her, attempting to build a positive relationship with him to overcome his initial fear. Her role in the story is that of a supporting character and a close friend to Tohru and the other dragons. She often appears as comic relief, with her presence frequently leading to humorous situations due to her otherworldly nature and lack of understanding of human social norms, particularly regarding modesty. Her most significant relationship is with the magician boy in whose home she resides, and she also shares a strong bond with Tohru and the other dragon refugees in the human world, such as Fafnir and Elma. Over the course of the story, her development is subtle but involves her further acclimating to human society, even if she still frequently causes minor incidents due to her divine power and carefree attitude.

In terms of notable abilities, as a former goddess, Coatl possesses immense magical power that far exceeds that of most dragons. She is a powerful wizard capable of feats like altering her environment and cleaning up large-scale magical destruction. One of her demonstrated abilities is the offer to completely clean a park after a destructive dodgeball match between dragons and also erase the memories of any human bystanders who witnessed the supernatural event, showcasing her power over both physical matter and the minds of humans. Her physical appearance is noteworthy: she has mismatched eyes, with one being black on the outside and yellow on the inside with a green slit pupil, while the other is green on the outside with black on the inside and a yellow slit pupil. She also possesses horns, wavy blonde hair, and very distinctive attire, often wearing revealing outfits that purposefully draw attention to her role as a fanservice character.