This is a family matter, Mr. Harper, and you are not family.
Roy: You are poison. You put her in Ra's al Ghul's gun sites. You had her kill Sara.
Malcolm: Thea knows nothing about Sara and she never will.
Roy: That's where you're wrong. I know her. She'll get to the truth no matter how good you think you're hiding it and when she does find out you've been lying to her, you're gonna lose her forever. Trust me, I know it from experience.
Malcolm: This is a family matter, Mr. Harper, and you are not family.