Avinia is a young monster rider from an isolated village of Riders. After the Black Blight destroyed her home, she fled with her Monstie, a Barioth named Frostfang. This tragedy shaped her initial cautious and distrustful nature, leading her to hide her feelings from others.

She travels constantly with Frostfang, their deep bond forged through shared hardship reflecting unbreakable trust. Her journey eventually brings her into contact with other Riders, like Lute and his companions from Hakum Village. Despite her loner tendencies, she gradually reveals a kind and loyal nature to those she accepts as friends.

Avinia has blue eyes and blonde hair, typically worn in a ponytail. Her white Barioth armor features fur trim and a Kinship Stone attached to the center of her chest. Later depictions, such as in the anime, show her noticeably older and taller.

Her background includes seeking the Channeler to perform the Rite of Channeling, an endeavor interrupted when a Khezu attacked her, leading to rescue and connection to broader narratives about the Black Blight threat. In Monster Hunter Stories 2: Wings of Ruin, she participates in rebuilding her home, Kuan Village, focusing her energy on its restoration. The sequel also details how she first met and befriended Frostfang.

Avinia wields specialized equipment, initially using a Lumu Horn in early gameplay segments of Monster Hunter Stories 2 before switching to a Bariguiro in the postgame. She remains the only Rider who uses a Hunting Horn across the games. Trivia notes highlight her fondness for Felyne paw pads and her unique tolerance for bitter drinks created by Lilia.