[s4e5] I Hear You Knocking Here

: The Hollow manifests as his abusive father, Mikael. These hallucinations taunt Klaus, suggesting he is weak and that the only way to protect his daughter, Hope, is to revert to his most brutal, murderous self by killing Marcel.

: Hayley discovers that her parents were murdered by Mary’s husband while he was under the influence of the Hollow. [S4E5] I Hear You Knocking

" I Hear You Knocking " is the fifth episode of the fourth season of the CW series , which originally aired on April 14, 2017. This pivotal hour serves as a psychological deep dive into the show's two most complex power players, Klaus Mikaelson and Marcel Gerard, as they are forced onto a violent collision course by a malevolent entity known as The Hollow . Psychological Warfare: The Hollow’s Manipulation : The Hollow manifests as his abusive father, Mikael