A Devious Brother (Remnants of the Fallen Kingdom) by Day Leitao

Ancient evil has awakened, and blood calls to blood. When the Witch King awakes from three centuries of slumber, Astra must find a way to prevent him from escaping his magical prison. Joined by an ally as mysterious as untrustworthy, she has to navigate treachery and old oaths for a chance to save the world as she knows—and the prince she loves. Surrounded by enemies and with his magic tracked, Marlak learns that the key to save his wife and friends is the element he swore never to use again. To wield it, he’ll have to overcome the horrifying echoes of his past. Meanwhile, the Witch King’s reach grows hourly. Astra and Marlak will need the support of an unlikely group of heirs and outcasts including former enemies and begrudging allies. If they hope to stand a chance against the Witch King’s thrall, they’ll have set their pride aside and overcome old wounds. Whatever they do, they must act fast, as their days are numbered and their doom is closer than they think. Read more