The Serpo are often seen sporting grey-skinned, outwardly male humanoid disguises. These disguises share a common outfit consisting of white, collared button up shirts tucked into grey dress pants, leather belts, and brown shoes. The heads of the disguises are notable for their thin lips which are drawn into incredibly wide and disconcerting smiles.
Out of their disguises, the Serpo have angular, slug-like heads with large, prominent lips and broad teeth. Their bodies are broad and sharply angled around the shoulders and torso. Black markings cover most of their bodies. They have two fingers and two thumbs in each hand, and their feet are clefted at the ends. Serpo also possess a set of headlight-like crystalline eyes whose color varies between individual Serpo, such as pink, yellow, cyan, red, green, or purple.
The Serpos scheming.
The Serpos' true form.
The Serpo are forceful and violent towards humans when abducting them but are otherwise oblivious to this, believing that their actions are peaceful. Another interest they have are the supernatural abilities of humans who have gained powers from spirits, since those powers often surpass the capabilities of the Serpo's already highly advanced technologies.
Other than being obliviously hostile towards humans, the Serpo are brunt and cold towards their subordinates, having no concern for their hired help's well-being and viewing them as nothing but cheap and easily replaceable. While the Dover Demon took on the task of fighting Momo, Okarun and Aira, the Serpo attempted to spur him during his poor performance by deducting his salary and injecting him with a mutagenic fluid meant to give him increased speed and strength (in spite of his objections).