Momon is a sentient stuffed toy crafted by desert fortune teller Éclair. Unable to acquire cotton at the market, she fashioned him from yellow fabric and feathers. Life sparked within him when Éclair's half of the Phoenix Stone emitted a mysterious glow that enveloped him, establishing him as her companion.

Physically, Momon possesses a large head adorned with a small tuft of feathers, a small beak, and round eyes. His body features small wings, feet, and a tail. He is primarily yellow and wears a turquoise shirt.

Momon demonstrates unwavering loyalty to Éclair. After her initial rejection, stemming from distrust of magic, he persistently follows her. He protects her from desert wolves, retrieving her lost Phoenix Stone despite sustaining injuries. This act earns Éclair's trust, leading her to formally name him "Momon" – derived from "momonga" (flying squirrel), reflecting her original design intent. He accepts this name despite his bird-like form.

Accompanying Éclair to Magnolia, Momon seeks help from Lucy Heartfilia when Éclair collapses. He mediates between Éclair and the Fairy Tail guild, frequently apologizing for her hostile demeanor toward magic users while affirming her underlying kindness. He remains steadfastly by her side during encounters with the Carbuncle guild and explorations of Boundary Forest, where they discover her father's recorded message about the Phoenix Stone.

In the climax, Momon attempts to rescue Éclair from a ritual pyre after her capture. Ignoring his injuries, he flies into the flames to break her chains and is consumed by the fire. Following the Phoenix Stone's destruction and Éclair's subsequent death, his spirit reunites with hers as they ascend to the afterlife together.

Momon's sole established ability is flight, achieved through his small wings. This capability facilitates his desert rescue of Éclair and his final attempt to free her from the pyre.