Ending Explained: Malignant

💡 What does the ending really mean?

It is revealed that the mysterious killer, Gabriel, is not a ghostly or demonic entity, but Madison's parasitic teratoma twin who shares her brain and nervous system. When Madison experiences trauma or hits her head, Gabriel takes physical control of her body, moving backwards (with inverted joints) to commit atrocious crimes. Madison manages to mentally 'lock' Gabriel in a mind simulation and reclaim absolute control of her body to save her sister Sydney. However, Gabriel remains dormant inside her skull, promising to return when Madison is weak again.