Mother — Ending Explained

The Truth: Do-joon did kill the schoolgirl, Ah-jung. She followed him, he propositioned her, and when she rejected him and called him a 'retard,' he threw a large rock at her head in a fit of childish rage. He then dragged her body to the roof to 'so she could be seen,' not understanding the gravity of death.

The Cover-Up: The Mother finds the Junk Collector who witnessed this. To protect her son, she smashes the old man's skull with a wrench and burns his house down to destroy the evidence.

The Tragic Irony: The police eventually arrest another intellectually disabled boy (Jong-pal) for the crime. The Mother visits him and cries, realizing he has no mother to protect him like she did for Do-joon. She leaves him to take the fall.

The Ending: On a bus trip with other parents, the Mother stabs her own 'forgetting' acupuncture point and dances manically, choosing to erase the memory of her son's guilt and her own crimes.

The Freudian Reading: Many critics view the relationship as deeply Oedipal. Do-joon sleeps in his mother's bed, and her obsession with him borders on romantic jealousy. His violence is a result of this suffocating intimacy.

The Political Allegory: The Mother can be seen as representing the 'Old Guard' of Korea—willing to destroy the truth and the future (the young girl, the witness) to protect the incompetent status quo (the son). Her 'forgetting' at the end mirrors a society that chooses to ignore its dark history to maintain comfort.

The 'Do-joon is a Genius' Theory: A minority fan theory suggests Do-joon is not disabled but a psychopath feigning disability to manipulate his mother into cleaning up his messes, though most evidence points to genuine disability and impulse control issues.