That would be Siren, while we don't know which role that she'll play in ARR, she is a primal. I'll assume, based on the rest of the pictures, that it is a mere coincidence that she appears behind the summoner and that it is simply a demonstration of her in-game model.
There is perhaps no phenomenon which contains so much destructive feeling as moral indignation, which permits envy or to be acted out under the guise of virtue. - Erich Fromm
