As not to become an unintended spoiler for the novel, I've confined my characters to those who begin the story with Scott.
Scott is half of the novel's main character - gifted and tormented at the same time by Water, the siren sharing his mind. Emerging from a tortuous childhood and confinement in a mental hospital, Scott uses the music he escaped into as a means for carving himself a new life as a world-class composer. His instrument of choice is a specially constructed oboe designed to do far more than play his famous symphony. It is the key to his ultimate escape from Water. Scott is a lean young man whose long brown hair helps cover the glittering blotches across his forehead from where he was pressed against a Reliquary as a baby.
Song Guard. Siren. She meant to die defending her Song, but instead of joining it in defeat, she transmitted herself into something else altogether - a human child. Having lived longer than any Song Guard should in the body of her hated foe, she spent her early life lashing out at her unwilling host until they both realized that neither would see freedom outside hospital walls unless they cooperated. So she sleeps, stirring occasionally to badger Scott with half-hearted hatred. That, or listen to his music. Like him, Water yearns to be rid of Scott's presence. As with all Song Guard, Water is man-sized, though her slender crystal body and face give her a feminine countenance. She has arms and legs that are more than capable for fighting on land. Strong fins drape her legs like a dress, while dorsal counterparts can be spread across her back to give the appearance of wings. She is protected by crystal plates, and marked by streams of bioluminescence reflecting her mood.
Scott's father is a hardened officer in the mercenary outfit known as Brothers. His wife and son are the only decent things he has, and he'll do anything to protect them. Even kill his own men and steal the one thing that can save his stricken son's life. He planned for everything except what happened when he touched his son's forehead to the Reliquary.
The Prophet was formally known as Frank Hanza, an anthropologist studying the Shreen culture. That career ended when he discovered both the Reliquary below the lake and the regenerative power it possessed. Frank switched his calling, and his name. Soon he forgot both. White suits and blond hair finish out the hollow sincerity of his invented life.
The Church of Life's newest celebrity started out with even humbler beginnings than the Prophet who canonized her. Mara Martinez, a dark haired Castilian asteroid pilot, was irradiated in a mining accident. She was retrieved from death's door by exposure to the Reliquary, and touted by Jeremiah Jones as a living miracle. She dearly wants to believe in God's gift but her faith is wearing thin as Jeremiah's chief huckster.
He prefers just "Mackenzie". There's little desire for close relationships in the no-nonsense world of a professional soldier. Mackenzie runs Brothers, a mercenary outfit in the pay of the Church of Life. He's not much of a believer in anything save for a person's honor, and there are debts to pay. Especially to Scott's father, Harry Rellant, who was once under his command. Mackenzie knows about Scott. Worse still, he also knows about Water. And he has been watching them both with narrowing eyes.
Everyone calls him "Benny". Even Scott is clueless as to his manager's real name. Benny goes to great lengths to be what everybody expects of a rock star's agent - right down to the flamboyant clothes and manners. He's good at what he does, and for fifteen percent he ought to be. Behind the bright smile and garish attire is a street-wise man who's seen it all. At least Benny thought he had.