Devin Fermin-Grav is the daughter of Keith Fermin and Gus Grav. She is a Subterra brawler partnered with Rex Vulcan, and is a member of the Vestal Division.
Devin is an 8 year old Vestal girl. She has lightly curled blue hair with long bangs. Her eyes are big, round and green.
The polar opposite of her big brother Derek, Devin is a happy-go-lucky and playful girl. She is easily excited and full of relentless energy, and can easily make friends. Devin can actually be somewhat stubborn, although she is easily swayed due to the fact that she is very gullible and easily manipulated.
She cares deeply for her big brother and her other friends, but especially Derek. She stands up for her friends, no matter if she understands the situation or not - chalk it up to a little girl's naivety.
Despite her young age, Devin is well-versed in the workings of Vestal technology.
- Father: Keith Fermin
- Father: Gus Grav
- Older Brother: Derek Fermin-Grav
- Paternal Grandfather: Clay Fermin
- Aunt: Mira Fermin
- Uncle: Ace Grit
- Cousin: Alannah Grit
- Cousin: Caleb Grit
Derek is Devin's adoptive older brother, and is very overprotective of Devin. Devin looks up to Derek and since Devin doesn't battle often, is usually cheering him on from the sidelines.
Devin is Shiori's "partner-in-crime." She helps Shiori come up with the pranks she plays on other people and also plays with her when their pranks fail.
Devin and Neville are close friends. Devin shares Vestal technology with Neville, and also recruits him for her and Shiori's various schemes.
Jin and Devin are close friends. Sometimes she recruits her for her and Shiori's schemes.
- Devin was born through the process of surrogacy. Her surrogate mother is her aunt, Mira Fermin, and Devin's biological father is Gus.
- Devin was originally a young boy named Dmitri, who then was renamed Devon. Then, she was given a gender change and her name got a change to make it more feminine looking.