Amon is a minor yet visually distinctive character in the narrative, serving as one of the two constant bat-like familiars who accompany the demon Dantalion. Amon is almost always seen together with a counterpart named Mammon, and the pair of small creatures are rarely apart from their master. In their default form, they appear as tiny, flying bats that flutter around Dantalion, often perching on his shoulders or hovering nearby.

Despite their diminutive and seemingly insignificant size, both Amon and Mammon possess the ability to transform into the form of young human boys. This ability to shift between a bestial and a humanoid appearance adds a layer of versatility to their role as familiars. Their personality, however, is not explored in great depth within the main storyline. They function primarily as extensions of Dantalion, commenting on situations or reacting to the events unfolding around him. Their presence adds a touch of dark whimsy, and their small size often contrasts with the more imposing figures of the demon nobles.

In the context of the story's hierarchy, Amon is not an independent agent but is firmly bound to Dantalion, who is a Grand Duke of Hell and a primary candidate to become the acting ruler of the demon world. The role of Amon and Mammon is largely observational; they witness the interactions between Dantalion and the human protagonist, William Twining, as well as the various political machinations of Heaven and Hell. They do not drive the plot forward through their own actions but instead serve as constant companions to one of the central characters, reinforcing his status and providing a visual reminder of his demonic nature. There is no substantial development or change to Amon's character throughout the series, as he remains a static and loyal familiar from his introduction to the conclusion. His notable ability is the capacity to shift from a bat-like creature into a human boy, though he demonstrates no other significant magical powers independent of his master.