Sizhui Lan

He was born Wen Yuan, the last surviving blood descendant of the Qishan Wen Sect, and was among the Wen remnants taken in by Wei Wuxian. After the first siege of the Burial Mounds, Lan Wangji found him at about three years old. He then fell into a high fever and lost his memories. He was renamed Lan Yuan and later presumably given the courtesy name Sizhui.