Chronicles of Tenek Lua Ben. Terror And Wave, #1

Life's greatest challenges are easier met with a friend beside you. An outcast from birth, Tamarin hides in the trees or works quietly in her father's infirmary to avoid the prying eyes of her village. But when her father leaves a willful boy with a bleeding head in her care, she finds more than a patient. She finds a friend. Lost in a sea of siblings, Adden is drawn to the brilliant, golden-eyed girl of his village.
His plan to impress her by riding a wild sea creature goes terribly wrong, but having her as his caretaker is a stroke of luck-and the perfect opportunity to get to know her. The two form a friendship that deepens as they explore the wonders of their island home-from ancient trees and hidden caves to strange and colorful creatures. But growing up comes with its own hardships, and the absence of Tamarin's mother has left a void that even their friendship can't fill.
With her mother's origins shrouded in secrecy, and her father refusing to share them, Tamarin feels stuck between a world that doesn't want her and a world she'll never know. When foreigners arrive on the shores of their island, everything changes, and the secrets locked away in the past resurface-revealing an outside world full of danger, dark forces, and a being powerful enough to destroy everything.