Villianess Grandpa

He is an immortal that is bound to one area. She is a princess driven from her home. He tells her, "There are only five rules you need to follow." 1: Kill without hesitation. 2: Never listen to the enemy, kill before they attack. 3: If you see the protagonist, kill on sight. 4: My word is the law. 5: Look at rules 1-4.