Like i said in another reply, be kind to all characters then head to the dungeon in the basement and free the crying orphan using the key you get from doing the kings quests and then beat the game from there.
You need to choose to let go/don't resist everytime the game gives you a chance to fight the darkness. He'll tell you he'll help you and you'll disappear and reappear one year later, agree to bind your souls and he'll rescue you from the mirror later
