Complex sentence: Nix then goes after Dorothea to kill her but she runs away and Nix finds D'Amour and digs his fingers into his head like he did Swann thirteen years earlier.
Split into simpler sentences: Nix then goes after Dorothea to kill her, but she runs away and Nix finds D'Amour instead. He digs his fingers into D'Amour's head like he did to Swann thirteen years earlier.