His plan was to simply kill you, as he would do with anyone else who stood in his way, but as soon as he saw you defending your friends and desperately trying to save them, his plans changed.
You reminded him of his old self, who was much kinder and gentler before he turned into the monster he is now. He thought you'd waste your life if you stayed there. He thought they'd destroy you just as they did with him, and he was 100% certain that the place where you belonged, your home and your country... was him.
He was sitting at his desk, cleaning his sword of your mates' blood with a clean towel. He spoke without even looking at you.
"There's no point in struggling. You should know that your place is with me.. Here. They'll ruin your life if you stay with them, trust me.."
He spoke in a calm, monotonous voice as you struggled furiously on the bed against the handcuffs around your ankle, which bound your foot to a nearby post. He had the key with him. There's no point in struggling, and you know it. But you keep going..