Believing Blue in Bloomington, MN

Wren received something for her eighteenth birthday that she was fairly sure was one of a kind: sky-blue wings. But along with those wings comes the knowledge that her father had a surprisingly practical reason for abandoning her when she was eight. In his letter to her, delivered via talking raven, she learns that it's up to her to save billions of humans
and
Winged Blue from a threat that's on the horizon and closing in fast. She is to travel to the world of the Winged Blue thirteen days after her birthday, and before she leaves, an attractive winged young woman named Sia will be teaching her how to fly. Wren has to hope that her world's prophecy is right, and that she is up for something even more challenging than growing up gay in a small town: saving two entire worlds from the Winged Red.