Marco had two regular guards assigned to his aunt's quarters after he had left her. While he had no doubts that she would be no trouble; now that she was locked away in her mind, but there was always a minuscule chance of her breaking free. He'd considered completely shut her down like Lawrence, but was happy he hadn't..
'The look in her eyes was worth the risk.. Besides, I doubt she has the willpower to fight me now..'
As the thought crossed his mind, a malicious smile stretched across Marco's face. He was surprised to realize that he'd always secretly resented Marie for her favoritism towards Tidas. But all the revelation did was make him find more pleasure in her suffering.
Marco recognized how twisted of a person he was, and fully embraced it. He had seen how people really were when society wasn't looking, and felt no pity towards such self-destructive creatures. Not even ones like Marie, who were actually good and decent.