Couple people actually asked about these things, so..'ere we go.

Eura's sub-type is a Sleeker Succubi, making her a sturdy one. The dark rubbery-tough chitin-like armor on her body is harder or softer in places for maximum protection and flexibility.

The series of marks on her jawline are very stretchy, to widen her morphed jaw when she needs to bite things!

Most demons have high shapeshifting abiltiies, Sleekers do not posses this beyond the usual plumbing editing as required for their proliferation.

Genetic mixes usually posses the chitin markings as the dominant trait when mixed with non-sleekers.

Sleekers make for good tracker/guard demons usually.

Eura is part of the first clutch of Sleekers.