Xiao Gu is the chief doctor of the Xiao Clan.
He devoted his life to medicine and neglected profound strength.
He cured Xiao Yulong's injuries after he was beaten up by Xia Qingyue.
Before Xiao Yunhai and the others framed Xiao Lingxi, he was informed beforehand so he won't screw up their plans, since they had a big backer as the Xiao Sect he didn't dare to refuse.
He also diagnosticated Xiao Yulong's situation after he was crippled by Yun Che.