Zhara has a personal reason to hate Seles
Even though she despises Chroma in general, Zhara is shown to hold immense dislike for Seles in particular, something that surprises even the latter, as she never tried to antagonize her. In their childhood, Zhara was in fact the one bullying her - and even back then Seles couldn't defeat her, so Zhara can't resent her for having humiliated her with her powers. However, talking with the head of the orphanage reveals that when she was younger Seles was kicked out because she accidentally set the place on fire with her powers, since she had a hard time controlling them. Maybe someone Zhara cared about was hurt or killed because of an accident caused by Seles' powers (such as the fire), and Zhara is blaming the latter for it.- Jossed. Zhara was jealous of Seles, feeling that being an Aion made Seles better than her. The story explicitly spells it out, as does the bestiary.
