Suggestions for a Hellhound OC?

I am currently working on a Hellhound oc and I wanted some tips on fleshing them out.

The character idea I had in mind is a large and intimidating hellhound character that would probably tower over most characters besides Goetia and Sins.

I imagine her as kind of an outcast among others

I was thinking her name would be Roxy/Roxanne

I mostly need some help on fleshing out her appearance, personality, and maybe bits of her backstory.

If anyone has any thoughts or suggestions for how to improve the character idea I am all ears