Mikasa knew from the beginning that her brother was different. He mentioned things that never happened as fact, shouted about 'the Titans', and claimed to want to be a member of 'the Scout Regiment'. He was always lost in the world of his own making. She could hear people whispering about 'that poor Eren, the boy is touched in the head.' They said he was a danger to himself and others.
Eren was her baby brother! Hers! And their parents wanted to send him away! Mikasa was mad and she had no qualms with expressing her cold rage.
"It's only for a little while, Mikasa." Her mother said, "Only for a little while, Eren will be home before you notice he's gone." Eren grinned at Mikasa.
"You're always so overprotective, Mikasa. I'll be fine. I'm not a little kid"
Far too soon for Mikasa's liking, they arrived at the facility Eren had been referred to. They were greeted by a tall, blond man with large eyebrows wearing a lab coat that had a name tag that read: Dr. Erwin Smith.
"Commander Erwin, Sir!" Eren shouted, giving the man an odd salute, right fist over his heart, left tucked behind his back. Dr. Smith's eyebrows raised a bit.
"At ease, soldier." Dr. Smith replied. Eren returned to his former position.
"You'll take care of him, right?" His mother asked worriedly, "You can make him better and then he can come home?"
"Ma'am, I'm afraid that if you've been referred to here it's because, well, it's because he won't be able to function safely in society."
"So, my baby has to live in the looney bin?" The woman sobbed. She wrapped her arms around Eren, pulling him to her chest.
"Ma'am, the patients here aren't looneys. They just have different needs. Your son needs special attention, more so than most children. Although he will have to live here, you aren't barred from visiting or sending mail." Dr. Smith comforted. Mikasa glared at the man.
"Eren!" Mikasa cried, grabbing his hand. Eren gave his sister's hand a reassuring squeeze.
"Don't worry, Mikasa. I'll be fine. Commander Erwin is here after all." Eren pulled his hand away.
"Right. Well, Eren, we've run out of empty rooms, so you're going to have to share. If you'll just say goodbye to your family and then pick up your bag and follow me." Eren eagerly said his goodbyes and trotted off after Dr. Smith.
"Now, Eren, your roommate might be a bit difficult for you to get along with. He doesn't care for messes and is very neat, so it would be helpful if you kept your belongings tidy." Dr. Smith explained.
"Yessir, Commander!" The doctor walked to a door and knocked.
"Levi? Are you there?" About a minute passed before the door opened revealing a slight, dark-haired, bored-looking, young man.
"Captain Levi, Sir!" Eren shouted, giving the man the same salute he had given Dr. Smith. Levi looked distinctly uncomfortable.
"What's going on, Erwin? Why are you and the brat here? Who is the brat? Why did he call me captain? What is he doing?" Levi asked in monotone.
"In order: You're getting a roommate. To get him settled. Your roommate. You've been promoted from lieutenant at some point. Saluting you." Dr. Smith said easily. Levi fiddled with his long sleeves.
"But my room is clean. He'll make it filthy and I'll have to clean even more." Levi protested, fighting back tears.
"I'll help clean, Captain Levi, Sir!" Eren shouted.
"Levi, we don't have enough rooms here for you to continue to have your own. You- "
"Alright, fine. The shitty brat can stay." Levi acquiesced. Levi showed Eren into the room and began to explain the rules.