Malcolm: Oliver, I know I wasn't there for Tommy, but I see Thea as my chance for redemption.
Oliver: You turned my sister into a killer and then you put her into the cross hairs of one of the most dangerous men on the planet.
Malcolm: And you won't believe me, but I did so with a heavy heart and expecting a different outcome.
Oliver: Ra's is going to come for me and he will learn the truth about Sara, eventually.
Malcolm: And then he will come for Thea. And me.
Oliver: That's why I have to kill him.
Malcolm: You couldn't before.
Oliver: This time I will have you to train me.
Malcolm: Only the student will have hope of defeating the master.