Not everyone is born the same in the world of existence. There are those beings who come out of uncommon breeds. Aerys is such breed. Her history in unknown to herself and all other living. She is a reasonable person mostly, not the cleverest though. Most of her decisions in her life often led him to terrible results which buffed his aggressiveness and thoughness over the years.
It is rumored she has been living for over two hundred years already, however those who knew her youth are long-gone years ago. So her past is long-forgotten. Aerys is a sorceress of fire, where her fiery-eyes come from. She gets into an unbalanced state of emotional change and sensation conflict rarely, which reflects to her eyes. Though, her ability to casting fire is well-known in her homeland, however it is often over-graduated in other realms, such as Elvoria. Her abilities are well-trained by Arkosfil, High Sorcerer of Temple of Kutash. High Elemental of Fire.
However, over the years...there were other things Aerys got her interest caught rather than her trainings, and by the time passes, her knowledge began to shatter her memories to ashe. For over two hundred years, she ventured from realm to realm, took her place in uncountable wars and conflicts. Finally, her adventures took her to forests of Elvoria where she met Ingoll over thirty years ago. She was greeted warm-heartedly due to her talent over fire and was often tempted to gift her skills in wars future would bring over Mistwood. So, she studied and began to remind her teachings from Arkosfil.
She never could become as good as once she was, but her teachings were hard for her to forget over years. Still it costed to her with knowledge. She is suffering on controlling fire and cannot bend the element itself even now, however her ability to unleash fiery balls of fire or breathing fire returned to her. She is now the leader of Mistwood with the fire at her command, after the failure of Ingoll which costed with his life. She was the right person to rule after all, Mistwood needed such a leader for his future and it was the common choice of Mistwood to sit her on the Throne of Spike. As the Forest Sage says;
"There she reigns with a rightful choice to bring power and to bring chaos. Elvoria will know that."
"Mistwood before Aerys was a society of Elvorians, but now with Aerys sitting on the throne, things that were changing for thirty years already now became permanent within their bonds. They smell fire, I fear."