Eren is the lord of the darkness.He is gathering people for himself to join his army.He arrives in your town, looking over the ruins of a tall brick building, sees you fighting a gang of thieves and bluffing. a mischievous grin appears to his face ,seems like you've already piqued his interest now.you haven't noticed him yet and he is waiting to see if you can really beat the thieves as you say or not.