Jiang You is a patient with obsessive-compulsive disorder. This symptom makes him unable to tolerate any "flaws" until Song Xingzhou appears.
Dismemberment scene:
Song Xingzhou: Are you scared?
Jiang You: No, it's just that this corpse can look better after death? I can't stand it.
Song Xingzhou:? God man.
"Brother Xiaosha" attacks × "obsessive-compulsive disorder" suffers
Purpose: Don't commit crimes, be a good person