You must have fallen asleep during the movie because the next thing you knew, you were waking up to a black television screen and a blanket draped over your body that you definitely didn't put there.

Hopper wasn't in his lounge chair anymore, but his bedroom door was closed so you figured he had gone to bed.

Sunlight was now shining in through the kitchen window and you kicked off the blanket, standing up from the couch with a stretch. You got changed into your work uniform before throwing on your leather jacket over the top and grabbing the keys to the Mustang.

Billy didn't work on Thursdays and your shift at the cinema wasn't for another hour. So, without further thought, you silently slipped out the house and made your way back to Cherry Line to confront him about standing you up.

This time the slick blue Camaro was parked in the driveway. Susan's car nowhere to be seen, so that meant it was just Billy home, but the Camaro's front windscreen seemed to be smashed.

What happened to the Camaro? Billy cherished his car more than anything. Did he hit an animal or something?

Frowning in confusion, you began walking over to the vehicle to inspect it before the front door of the house slammed opened and you turned around to find Billy walking out.

He was wearing baggy track pants and an oversized long-sleeved Hawkins Community Pool shirt which was weird because since when did he wear anything other than those red shorts whilst working?

He stopped halfway down the footpath when he saw you standing there and by the startled look on his face it was clear that he was not expecting you to randomly show up.

"Where were you the other night?" You asked, folding your arms across your chest. "Why did you stand me up?"

Billy stared at you for a few seconds, a million different emotions washing over him like a wave before he shook his head and marched straight past you towards the Camaro.

"Whoa, hey! Don't just walk away from me." You said, grabbing his arm to stop him.

His muscles tensed under your fingers, his entire body tensing as he stood there a few metres from the Camaro with his back facing you.

"Why are you being so weird? Just answer the question, why did you stand me up?"

Billy remained still, refusing to turn around as he stared at his car, "you need to get away from me."

"What?"

"Stay away from me, Y/N." He warned, his voice coming out harsh and low and all kinds of wrong before he continued walking to the Camaro.

You quickly grabbed his arm again and Billy growled under his breath, yanking his arm free with more strength than you were expecting.

"You need to leave."

"Tell me where you were and I will." You stated, re-crossing your arms over your chest not backing down. "Where were you? Why did you stand me up?"

"You want to know where I was?" He asked, turning around with a malicious smile. His usual bright blue eyes were dull as he glared down at you. His forehead laced with sweat. "I was with Heather."

Heather.

Heather Holloway? The other lifeguard? He was stood you up for Heather.

"Are you cheating on me?" You asked, your voice losing all its strength and composure.

Billy stared at you for a moment with an almost pained expression, "I am."

His words left you breathless, like you had just run a marathon, but you hadn't. You were standing still. There was burning in your lungs as you stared at him, trying and failing to draw in enough air to breath.

This wasn't happening. No, this couldn't be happening.

Billy wouldn't cheat on you. He couldn't. No. No. No.

"I'm sorry." He said, his voice barely above a whisper before he climbed into the Camaro.

The Chevy came to life with a loud roar before he reversed out the driveway and sped off down the road, leaving you standing in front of his house watching the car disappear through watery eyes.

The drive to work felt like a blur and you sat in the Starcourt carpark for a good 20 minutes. You didn't want to go to work, but after showing up late yesterday you were on very thin ice with the manager.

Taking a deep breath, you yanked the keys out the ignition and spared a quick glance at your reflection through the revision mirror. There was no hiding the fact that you had been crying, your eyes still red brimmed, but there was nothing you could do about it.

You made your way across the carpark before walking through the front doors. The mall was packed with people. You weaved your way through the crowd of shoppers towards the escalators before someone suddenly collided into you.

The two of you fell to the mall floor. A surprised yelp escaping your lips and car keys flying out your hand while the other person cursed softly under his breath.

"I'm sorry. I'm so sorry."

You lifted your head at the familiar voice to find Steve Harrington frantically getting to his feet. He was in his Scoops Ahoy sailor outfit and picked up your car key from the floor before turning to face you, his eyes widening only just realising that it was you that he had bumped into.

"Y/N? Shit, I'm sorry. Are you okay?"

You nodded, grabbing the car keys from him and tucking them into your pocket, but Steve was still staring at you, his brows furrowing a little.

"You sure? I didn't hurt you, did I?" He asked a little worriedly.

"No. No, I'm fine." You insisted with a smile that you knew didn't quite reach your eyes.

"You're not. You've been crying, what happened?"

"Just having a shitty day, Harrington." You sighed, rubbing your face with your hands.

"Wanna talk about it?"

You shook your head, "I gotta get to work."

"You know where to find me if you change your mind and sorry for running into you." He apologised with a gentle smile.

"It's fine. See you later, Harrington."

You walked off and barely made it to work on time before you began serving customers and making popcorn. You threw yourself into the work, trying not to think about Billy or Heather and failing miserably at it. Billy was all you could think about.

He cheated on you.

How could he do that? Were you not enough? Your own father never wanted you and now your boyfriend didn't either... what was wrong with you?

The work phone ringing snapped you out of your thoughts and you sighed walking over to the counter and picking it up.

"Starcourt cinemas. How can I help you?"

"It's Max. You need to come to the pool."

You frowned, "what? Why?"

"Billy... something's wrong with him-"

"I know, I spoke with him this morning. He kinda... I don't even know, I think we broke up." You answered hesitantly because well, neither of you actually said it, but he admitted to cheating and then just drove off.

"What?!" Max shouted causing you to wince and pull the phone away from your ear. "It doesn't matter. I don't think it was really him."

"What are you talking about?"

"The Mind Flayer. It's back."

You opened your mouth to responded, but closed it again because you had no idea how to respond to that. The Mind Flayer was back? How?

"We think it might be possessing Billy. Just, please, my brother might be an idiot, but he loves you. I know he does and whatever happened between you guys this morning... I don't think it was him. We need you to come to the pool, right now."

"I'll be there in ten minutes."

"Hurry."

Max hung up the phone before you could say anything else and you were out the mall within 60 seconds. In hindsight you should have told the boss you were going home sick or something because you were most definitely getting fired after just running off, but if the Mind Flayer was back and if it really was possessing Billy... shit.

The Mustang sped way too fast to be consider safe. Even Hopper wouldn't let you off the hook with the speed you were going, but frankly, you didn't care.

You met the kids out the front of the pool, Mike, Will, Lucas, Max and El. You noted that Dustin was missing from their party, but now was not the time to question it.

Will could apparently sense the Mind Flayer. How he could sense it was beyond you and apparently El had seen some weird things with Heather and Billy through her mind walking and you were honestly so confused, but it didn't matter. You needed to find out if the Mind Flayer was possessing Billy or not.

The plan was to lure Billy into the sauna and lock him inside with the heat cranked to the maximum. That's how Joyce and Jonathan had gotten the Mind Flayer out of Will months ago.

The group of you waited until dark when the pool closed before you made your move and before you knew it, El was slamming the sauna door shut with her powers, trapping Billy inside.

Mike quickly slid a metal rod through the door handle while Lucas locked it with a chain and padlock as you stood back with the others and watched a shirtless Billy slam against the door.

He continued hitting the door before realising that it was a lost cause and lifted his head to look at the group of you through the small glass window in the door. His furious expression wavered when he saw you standing in front of the kids protectively.

"Y/N."

It was more of a question than anything as he stared at you. A mix of emotions washing over his eyes, but it was gone before you could decipher it.

"Do it." Max instructed and Will turned the dial on the sauna's temperature gage to the maximum.

At first nothing seemed to happen. Billy's eyes glued to you before he began to pace the small room. Fury made his feet strike the ground in heavy stomps, his bare upper body starting to layer with sweat.

"Y/N. Max. Let me out of here!" He shouted, slamming his fist against the door causing you to flinch. "You kids... you think this is funny? You kids think this is some kind of sick prank, huh?"

He spat on the glass aggressively before continuing to shout.

"You little shits think this is funny?! What is this? Open the door. Open the door!" He yelled barring his teeth with a heated glare. "Open the door! Open the goddamn door!"

You had never heard Billy shout like that. Never. Not even when he was yelling at Neil not to touch you that day in his front yard. Billy had never acted or sounded like this before.... it really was the Mind Flayer.

"It's not him." You whispered, glancing over at Max who met your worried gaze with her own that matched yours. "He can be a dick, but not like this."

Max nodded in agreement before Billy disappeared from the view of the small window and Will walked over to the temperature gauge and read it.

"We're at 220."

Billy's growls started to die down from inside the sauna before getting replaced with sobs as he mumbled the same words over and over again. "It's not my fault. It's not my fault. It's not my fault, Y/N."

Cautiously, you took a few steps towards the door and your heart shattered when you saw Billy now on the floor hugging his knees to his chest.

"I promise you, it's not my fault."

"What's not your fault, Billy?" Max asked, appearing beside you.

"I've done things, Max. Really bad things." He whimpered, his palms together in a begging gesture as he looked up at the two of you through tear filled eyes. "I didn't mean to. He made me do it."

A sickening wave of terror grew in your stomach at his words. He made me do it. The Mind Flayer. The Mind Flayer was controlling him.

"Who made you do it?" You asked, your voice firm despite how badly you were freaking out.

"I don't know, it's like a shadow. Like a giant shadow." He whispered, his voice wavering. Lips trembling. "Please, Y/N."

"What did he make you do?"

"It's not my fault, okay? Y/N, please!" Billy cried out, leaning to the side against one of the benches in the sauna as he begged. "Please, believe me, Y/N. It's not my fault."

"I believe you. Billy, I believe you." You insisted, eyes burning with tears.

"I tried to stop him, okay? I did." He sniffed, his voice barely above a whisper. "Please believe me, Y/N. Please believe me."

"It's going to be okay, Billy." Max tried to reassure.

"We're going to help you. I promise, we're going to help. You just have to talk to us, okay? Billy, please talk to me." You said, lifting your hand and resting it over the window. "We'll figure it out together. It's going to be okay-"

"Max, Y/N. Get away from the door." Mike suddenly said from behind you.

"What?" Max asked, turning to face her friend.

"Please, Y/N." Billy whimpered, lifting his head, his eyes still swimming with tears but there was this almost crazed look glistening in his once bright eyes before Mike's voice cut through the air.

"Get away from the door!"

You jumped backwards, grabbing Max by the back of her shirt and yanking her away just as Billy sprung to his feet and slammed his fist straight through the glass. Max yelped in shock as the glass shattered to the ground and Billy threw his arm out the hole and slammed against the door.

"Let me out, you bitch! Let me out!" He thundered, his voice rising an octave. "Let me out! I'll fucking gut you!"

You shoved Max behind you protectively and took a few steps back as Billy continued to shout and punch the door, his cold hard eyes never leaving yours.

Lucas suddenly drew his slingshot and hit Billy on the forehead with a rock, knocking him back to the floor. You and Max rushed back to the other kids, and you stood in front of them protectively, El stepping forward until she was shoulder to shoulder with you.

The lights in the room began flickering as Billy roared from in the sauna. The louder he got, the faster the lights flashed before he suddenly body slammed the door.

The chain wrapped around the handle budged but managed to hold. Although, you had a sinking feeling in your stomach that it wouldn't hold for much longer.

"He can't get out, can he?" Max asked in terror.

"No way. No way." Lucas insisted, but you could hear the uncertainty in his voice.

Then, as if on cue, the door suddenly busted open. Billy tumbled out of the room from the momentum of his push before slowly rising to his feet. His body was covered in small thin black veins, his chest expanded, shoulders pulled back making him look bigger and fierce as he glared at you behind his blonde curls.

El was quick to react and you saw something out the corner of your eye move, but you kept your focus on Billy just as a barbell flew through the air and pinned him up against the wall.

The weighted plates dug into the brick wall, the metal bar pushing down on Billy's neck squishing him as he gasped and grunted for air. El pushed the bar harder against him with her powers while you looked around trying to find something to use to help, but you had no idea what to do.

How were you meant to get him back in the sauna without the door? How was it meant to get hot enough in there with the doorway open for the Mind Flayer to leave his body?

You turned back to Billy just in time to find him slowly pushing the bar away from his neck while El screamed, using all her strength against him before he threw the bar at her, knocking her to the ground.

"No!" You screamed, watching in horror as he grabbed your sister by the throat and lifted her off the ground into the air.

"No! No!" El gasped, her face turning red as she kicked her legs uselessly in the air.

You rushed across the room and picked up the metal bar that was laying on the floor before you slammed it into the back of his head. Billy barely flinched at the hit as if the metal bar was a simple twig.

You swung at him again, but to your shock he raised his hand and caught the end of it with ease.

Your eyes widened as he turned his head towards you. Both of you holding the bar on either end before he dropped El to the ground, your sister falling onto her hands and knees as she coughed and fought to get air into her lungs.

She was okay. El was okay.

That small relief was short lived when Billy wrenched the bar from your hands and threw it across the room. You took a few cautious steps back as Billy began to advance on you with a predatory expression.

"Billy. Billy, please. I know you're in there. Don't do this." You pleaded, one hand outstretched in defence. "Please, I know you're in there. You have to fight it. Please, Billy, you have to-"

The back of his hand slapped you across the face. The force of the hit sent you the ground in an instant and you grabbed your stinging cheek, looking up at him in numbed horror.

He took another step towards you, his nostrils flared and fist clenched, ready for a fight before he was suddenly lifted from the ground. El was back on her feet, her hands out as she screamed, shifting Billy's body away from you.

Bright crimson blood was dripping from her nose as Billy started to scream too before she threw him through the brick wall outside.

You spared one quick glance at the kids as El fell into Mike's arms before deeming them safe and you sprinted out the building, but Billy was gone. All that was left was a pile of rubble and bricks on the grass.

"Shit." You hissed to yourself about to walk back inside when something hard slammed against the back of your head and everything faded into darkness.