Once & Future is a young adult science fiction novel written by A. R. Capetta and Cory McCarthy. It is an Arthurian retelling and is notable for having a diverse cast of queer characters. Once & Future was released in 2019, and was followed up by a sequel titled Sword in the Stars, published in 2020.
Summary from the publisher:
King Arthur as you’ve never seen her! This bold, sizzling YA novel reimagines the Once and Future King as a teenage girl determined to save the universe from an evil curse.
My name is Ari Helix. I have a magic sword, a cranky wizard, and a revolution to start.
I’ve been chased my whole life. As a fugitive refugee in the territory controlled by the tyrannical Mercer corporation, I’ve always had to hide who I am. Until I found Excalibur. Now I’m done hiding.
When Ari crash-lands on Old Earth and pulls a magic sword from its ancient resting place, she is revealed to be the newest reincarnation of King Arthur. Then she meets Merlin, who has aged backward over the centuries into a teenager, and together they must break the curse that keeps Arthur coming back. Their quest? Defeat the cruel, oppressive government and bring peace and equality to all humankind. No pressure.