Lan Sizhui is a disciple of the Gusu Lan Sect. As a junior disciple, Lan Sizhui is both well-mannered and organized. He acts as the leader of the junior disciples in the Gusu Lan Clan during their investigations in Mo Village and treats everyone with respect and kindness regardless of status, including Wei Wuxian when he pretended to be the lunatic Mo Xuanyu. He has a kindhearted nature, expressing guilt that the Demonic Left Arm had killed four people in Mo Village and injured many in the Cloud Recesses. Observant and intuitive, Lan Sizhui also informs Lan Wangji that "Mo Xuanyu" appears not to be a lunatic. He also suggests that the arm has been aiming for their Clan, which Wei Wuxian later surmises to be close to the truth, as someone has indeed thrown the arm into the village to target them. Lan Sizhui sees beyond the black-and-white morality of the cultivation world, as he suggests that Wei Wuxian might not have been as evil as society claimed before knowing of the latter's identity. Despite his general maturity, Lan Sizhui is not above occasionally losing his temper and joining in fights, such as while he and a hundred other juniors are held captive in the Demon-Slaughtering Cave, or telling a lie to lessen embarrassment, such as his lie to Young Master Qin about Wei Wuxian's sleeping habits. In addition, he is hesitant to admit to fear due to his anxiety that Lan Wangji would disapprove of him.
(Source: Mo Dao Zu Shi Wiki)
