He tries to look Lucius right in the eyes as he speaks, his own warm and dark and full or conviction. He's speaking from the heart, here.

"The word 'redemption' comes from a root that means 'to buy back'. Don't give up on your soul or yourself, Lucius. If there's one thing I've learned in my years, it's that evil is not a condition, not an affliction. Evil is a choice. You are only what you choose. That alone is what makes you."