Franz Kafka (post 5) said that compulsive self-harm (e.g., suicidal behavior or self-mutilation) implies “a second person” inside (which means multiple personality)

“No one can crave what truly harms him. If in the case of some individuals things have that appearance—and perhaps they always do—the explanation is that someone within the person is demanding something useful to himself but very damaging to a second person, who has been brought along partly to give his opinion on the matter. If the man had taken the part of the second person from the outset, and not just when the time came to make a decision, then the first person would have been suppressed, and with it the craving” (1, p. 80).

“Suicidal behavior is extremely common in MPD [multiple personality disorder] patients…Self-mutilation—typically cutting with glass or razor blades, or burning with cigarettes or matches—occurs in at least a third of MPD patients” (2, p. 64).

Search “self-mutilation” for relevant past posts.

1. Franz Kafka. Aphorisms [1917-1918]. New York, Schocken Books, 2015.

2. Frank W. Putnam, MD. Diagnosis and Treatment of Multiple Personality Disorder. New York, The Guilford Press, 1989.