Old design for Mutya, Nadia's bound SIN/familiar.

In the tabletop RPG, CAIN, Forbidden Spirit form is the closest thing a bound SIN can get to its true form.
Exorcists with a specific blasphemy/psychic power (Bind) will allow their bound SINs to aid them in combat this way, kind of like Pokemon.

Speaking of Pokemon, I referenced some of them when initially designing Mutya; specifically Scolipede and Giratina.
Scolipede being obvious (centipede design and poison typing), and Giratina's design being snake-like to me (especially with Giratina's origin form).

I figured that a Pokemon-like design is a good starting point for me in regards to monster/creature design.

Also tried to incorporate a cobra's hood to Mutya's design because Centipede SINs in CAIN are able to shoot their venom like a sniper rifle at will, and then I though of spitting cobras and how they can defensively shoot venom at long ranges.
Coincidentally, spitting cobras just happens to be Nadia's favourite snake...

It didn't ruin spitting cobras, or snakes in general, for Nadia but they're not happy that they're stuck with a Centipede whose form is a twisted version of their favourite snake.