Fly Greena Aight is a researcher at the Astarian Research Facility.
When he was at a young age, he and Aaron Newt discovered the "angel" +Anima, Blanca. When he met Cooro and learned of his black wings, he befriended him and said to him "You know that +Anima of yours? When you're a bit bigger can I have it?" Cooro, not knowing what he meant, said yes.
In volume 10, he found Cooro and took him and his friends to the research facility and tried to convince Husky and Nana to give up their +Anima for Blanca and ending up failing, after the gang left (without Cooro). Cooro asked Fly if he was a manmade +Anima, Fly, not wanting to lose Cooro's trust, said "Yes, you have no mother or father. You were made by me and Aaron." This, of course, was a lie.
Later, he transplanted Cooro's crow +Anima into himself so he could fly with Blanca and he did so but soon after take off it was revealed that Blanca was too unstable and she distenegrated as Fly lost the crow anima and it went back to Cooro.