Kieran had already made his choice and Iris knew that she couldn't remain useless and weak anymore. That was why she had immediately resumed her training and was studying under Melissa's guidance, wanting to master how to use her light magic. As her mentor suggested, Iris continued to feed her remaining dark magic to the wyvern, who was now growing rapidly under her care.
She hadn't bestowed it a name yet, because Kieran had told her that her magic wouldn't be enough to establish a bond between her and the wyvern. However, Iris and the rest of the court knew that the black wyvern wouldn't listen to anyone but her. Perhaps it was because she was the source of its nourishment that the wyvern would tail her around Aisgarth like a puppy. Regardless if she had named it or not, the wyvern was quite protective of her.