Levi and the others went to the Underground to go to the Orphanage because of the issues about the food supplies for the kids and also the syringe for Hange's experiment.

But levi let his own cadets take charge and just walked around to see what is happening around the area and sighed. Since he remembered you and him used to grow up in this place- Wait..

He then saw you from the distance, he thought he had saw you dead.. Then shouted. "Hey you! Come with me."