From A Youth A Fountain Did Flow

Supernatural meets Down Among The Sticks and Bones, a novel about the personification of the Fountain of Youth as a teenage girl. "...never dull...a neat twist on the concepts of the fountain of youth and reincarnation." -Kirkus Reviews.
In a world teetering on the edge of darkness, Scarlet Singer's life takes an unexpected turn when she becomes the center of a war between witches and demons, each vying for control over her regenerating body and the powers it holds. As Scarlet grapples with her own identity and the powers awakening within her, she finds herself confronted with a dark destiny that threatens to consume her.
When Scarlet stumbles upon a 19th-century journal, she must face her greatest fears and accept the possibility that she is the Fountain of Youth reincarnated. She must embark on a quest to discover the things that truly make her human. Scarlet is faced with an impossible choice: embrace her extraordinary gifts and risk losing her humanity, or reject her destiny and the powers that could save her.
"A fast-paced, intriguing, richly written puzzle box of a book. Every twist and turn left me breathless. That first paragraph grabbed me and wouldn't let me go." -Aaron Michael Ritchey, award-winning author of The Sages of the Underpass and The Cunning Man series.
"This is a captivating tale about witches and demons and a battle as old as time. It is a story of love, loss, and being captured by purpose. The main character is likable and brave, and her growth as she discovers the truth about her past and her power over the future makes a story well worth reading. I highly recommend it!" Cheree Alsop, best-selling author of The Silver Series.