After Levi becomes distressed about the fact he can't have kids with Eren, and the adoption agency finding them to be unfit parents due to Erens job, Eren gets Levi his baby in a different way.
This is basically an Ereri Cinderella story.
After Eren's mother Carla died his stepfather Grisha took him in to live with his step brother and step sister Jean and Mikasa. They don't treat him as family but as a servant. One day he meets the prince while attending his royal ball. He had to rush home and by doing that he left his high top behind. The prince uses this as his clue to try to find the boy who he had fallen for. Will Prince Levi find his true love or will he have no such luck in finding Eren.