Of all the insubordinate habits Eleven displayed, by far the most difficult to break was the humming. Like most children, she would improvise and hum little tunes under her breath. That alone would be grounds for discouragement as it was a distraction from her tasks. However, when she started humming songs it would be impossible for her to know, popular songs on the radio and traditional children's songs, the first assumption was that supervisors were careless and exposing her to them, but increased surveillance proved it false. Perhaps it was a demonstration of a new ability to pick up radio waves. Such a capability could prove useful, yet investigations of local radio stations were inconclusive; the songs she hummed were never being played at the same time. Since they could not control the habit, it had to be terminated.
However, despite their most concentrated efforts, Eleven continued to hum.
They tried rebukes and scolding.
They tried withholding privileges, such as recreational time or mealtimes.
They even tried locking her in the detention room.
Questions could be ignored and silenced. Disobedience could be punished.
But humming?
Naturally, after so many punishments, it was quieter, but not nonexistent. Eleven would only hum when she was completely alone, in her sleeping area or even the detention room.
The punishments continued, for surveillance never left her truly alone. But her humming continued until the day she disappeared.

Mike had always been a singer. He never sang in public, was never in the choir or Glee club at school, and rarely even sang in church. But in moments when he thought he was by himself, he would sing quietly under his breath, usually songs from the radio or, when he was younger, nursery rhymes. But there were other times when Karen would happen to walk in on him singing a new song, one without words. When she'd ask him what it was, he would shrug and say it just came to him. For a while, she'd hoped that meant he was a musician, but piano lessons crashed and burned, guitar lessons lasted barely a month, and the only writing he seemed interested in was writing campaigns, not compositions.
But his singing continued. She'd catch him in little moments, doing his homework, cleaning his room, all the while a song under his breath. She supposed it comforted him. He often came home from school discouraged, but always explained it as just being tired, although she noticed any exhaustion disappeared when the boys arrived for another campaign. She didn't ask. He needed his space and if music gave him some comfort, she wasn't going to discourage it.

For a long time, it hadn't seemed like things would ever go back to normal. Everyone knew it was impossible after everything that had happened over the past two years, but there was still that lingering hope and yearning for calm and comfort. And it came. Eventually. There were days of tears and pain that would never completely leave, but there were also days of peace, where the pain wasn't quite so sharp. It was on those days that Joyce would notice a faint melody coming from El's room at the end of the hallway and she'd turn the television or radio down a few notches just to take that breath of relief because today was a good day. It was on these days that Karen would smile quietly to herself as Mike swung downstairs into the basement, another song on his lips, the days of dark circles and sleepless red eyes over.
It was on one of these days that Mike woke up with a song stuck in his head. It happened to everybody from time to time. His grandma used to joke that it meant his soulmate was actually singing it, that they were connected by the beauty of music blah blah blah. He thought it was corny, since most of the time it was just a song from the radio or a crummy commercial jingle. But some days, like today, it was a song he'd never heard before but couldn't seem to shake. He didn't know if it was his soulmate (and he couldn't help how his mind went directly to El on that point) or if he was secretly a musician, like his mom had thought for the first ten years of his life. Either way, it stayed with him all morning, through lunch, and was still repeating in his head when the bell rang for the end of the school day. He raced Lucas home and then kept on riding all the way out to the Byers', since it was his day to see El. When he got there, Jonathan answered the door.
"Hey Jonathan. Hey Mrs. By-"
"Shh!" she pushed herself up out of her chair just enough to poke her head over the top and wave her hand to quiet them, simultaneously pointing down the hall toward El's room. Mike strained to hear and when he could finally make it out, he could swear his heart stopped.
She was singing the song.
There weren't any words, but she was humming it all the same. He felt the familiar warmth of a blush creeping up his neck and ducked his head, faking a cough to hide it.
"Can I go-?" he mouthed, pointing down the hall toward El's room and after she nodded, he stepped quietly down the hall and poked his head in the doorway. El was sitting cross-legged on her bed, a textbook on one knee and a notebook on the other in which she was calmly penciling in an answer. He was now even more sure that the song she was humming was the one that had been stuck in his head all day and suddenly he wondered if all those other unexplained ones had stuck with him for the same reason. He gently cleared his throat and El looked up.
"Mike!" she said with a smile.
"What were you singing?"
For a millisecond, her smile faltered, a tiny fracture, and she looked down and shrugged.
"It was nice," he offered, hoping she knew that the lopsided smile on his face was proof that he meant it. She looked back up and the fracture was gone.
He stood awkwardly in the doorway for a moment before he remembered she had no idea what he was thinking and was probably wondering why he was just standing there staring at her. He sat on the foot of her bed and chuckled.
"Okay, so this is going to sound really weird, but that song you were just humming? It's been stuck in my head all day."
"Really?"
Mike nodded. "Yeah. It happens a lot," he shrugged, smiling at her thoughtful expression.
"Me too," she smiled.
"You too?"
El nodded, a sparkle in her warm brown eyes. "You were singing that song yesterday. It was…" she paused, trying out the expression. "Stuck in my head, too."
His stomach flipped and he had a crazy thought about telling her what his grandma said. No, he thought, it's too corny. But the words were already out of his mouth:
"My grandma used to say that's what happens when people are soulmates."
He watched El raise her eyebrows and inwardly groaned. The words had come bubbling out, like when someone shook a bottle of soda and took off the lid before the carbonation had settled so that a stream of foam and soda spurted out of the bottle, covering the counter and floor in a wet sticky mess.
"Soulmates?" El repeated.
"Yeah, I know, it- it's corny," he said, sighing and running a hand over the back of his neck.
El shook her head, smiling in that heartmeltingly gentle way of hers. "It's not corny."
Mike looked down, struggling to keep the smile off his face. "Okay."
"I like being your soulmate."
He looked back up and didn't even try to stop smiling, especially since seeing El's smile and not smiling was pretty much impossible.
"Me too."