Resonance Surge by Nalini Singh

Where are the broken? That is the propulsive question that unleashes a world of secrets in New York Times bestselling author Nalini Singh’s Resonance Surge . . .
StoneWater bears Pavel and Yakov Stepyrev have been a unit since birth, but now Pavel’s life is veering in a new direction, his heart held in the hands of Arwen Mercant, a Psy empath—and the only man who has ever brought Pavel to his knees.
This is it. A point of irrevocable change. For Pavel . . . for Arwen . . . for Yakov . . . and for another pair of twins whose bond has a far darker history.
A low-Gradient Psy, Theodora Marshall is considered worthless by everyone but her violently powerful twin, Pax. She is the sole person he trusts in their venomous family to investigate a hidden and terrible part of their family history—an unregistered rehabilitation Center established by their grandfather.
Places of unimaginable pain designed to psychically wipe minds, leaving the victims shells of their former selves, the Centers are an ugly vestige of the Psy race’s Silent past. But this Center was worse. Far, far worse. And now Theo must uncover the awful truth—in the company of a scowling bear named Yakov, who isn’t about to take a Marshall at face value . . . especially a Marshall who has turned his dreams into chilling nightmares.
Because Yakov is the great-grandson of a foreseer . . . and he has seen Theo die in an unstoppable surge of blood. Night after night after night .