Grandmaster of Demonic Cultivation: Mo Dao Zu Shi (Novel) Vol. 3

The bloody war against the Wen Clan once led Wei Wuxian to seek power in demonic cultivation, and the dark acts he committed drove a wedge between him and Lan Wangji. Now, those old sins come back to haunt him as his reincarnated identity is revealed to the cultivation world. But even as the other clans call for Wei Wuxian's death, Lan Wangji stands by him, making Wei Wuxian realize what he took for disapproval in the past might have been a much deeper emotion.

The novel series that inspired the live-action drama, The Untamed!