Mike Wheeler and Will Byers are soulmates. They don’t know it yet, but the eventful events of Will being taken away changes that, and they’re never really going to be the same. 

When the Demogorgon gets Will to the Upside Down, Will is so scared, he feels like his whole word has just vanished right before his eyes. What was supposed to be a normal day became the most terrible nightmare that he could have ever thought of. He’s all alone, in a world where everything is so cold, trying to escape and stay alive in front of a monster that could possibly kill him and everyone else. He still fights though, because if there is one thing that he hasn’t lost yet is the hope of being able to see his family, his friends, again. 

On the other side of the world is Mike, who for all intents and purposes feels like he’s lost an important piece of himself the day he receives the news of Will’s disappearance. There’s a dull pang inside his chest that doesn’t seem to go away no matter what, it’s making it hard for him to breath normally, to the point he feels his lungs struggle to get more air inside. 

No matter how much time passes, it doesn’t get better. It’s like his entire body is slowly shutting down, day by day of Will still not being found, still lost to the world. It only gets worse when he’s there, with everyone else, by the lake, watching as they take Will’s body out of the water and this time he can’t breath at all. He’s hurting so bad and he tries so hard to just get some, any, air inside his body but it’s not working, everything in him is collapsing, his entire world stumbling down and becoming dust at his feet. 

Mike takes his bike, starts to pedal as hard and fast as he can. He doesn’t know exactly where he’s going, and even if he tried he wouldn’t get that far what will all the tears dampening his cheeks and blurring his vision. He goes and goes until finally he can see his destination in sight, his home. 

He doesn’t stay there much, only going inside, blurry vision still making it a little hard to navigate around but managing to get up to his room, grab what he was looking for only to get out of the house again. He ignores the calls from both his mother and nancy, asking him ‘what happened’ and ‘what’s wrong’. 

This time, he doesn’t take his bike as his hands are a bit occupied. He starts walking, wiping the tears from his face and holding tightly onto the precious portfolio he has full of Will’s art that he has done for him over the years. This time he knows where he’s going, having slowed down while walking, taking his time thinking about what exactly happened that night and what it would mean for him in the future. 

He’s so very deep in his thoughts that he doesn’t realise he’s actually arrived right where he was heading. 

Castle Byers is still the same as always, the branches still holding it very tightly together, with its flags fluttering gently with the night breeze. Inside is also pretty much the same as Mike remembers. Small but cozy, pieces of Will’s art scattered around and pinned to some of the branches, the makeshift ‘bed’ littered with comics and books Will probably was still reading, the small table in the corner full of drawing supplies and other small things that Will had brought over time. 

Mike makes his way slowly inside, taking some of the comics and placing them on one side so he can sit down. He cautiously places his portfolio beside him and starts taking Will’s drawings out from it. There are sketches, landscapes, portraits and more inside it. He looks at each and every one of them, giving them his absolute attention, his eyes taking in every single detail possible. 

At some point, his vision blurries again and he doesn’t notice he’s crying until he sees droplets of water on the papers he’s currently holding. He hastily wipes them away, not wanting to mess up the drawings and it’s in that moment that he hears a faint noise in the back of his head. It’s a bit hard to make out what it’s supposed to be since to Mike it seems as if it was coming from somewhere far far away. He goes completely still, trying to not make any sound to see if he can hear the faint voice again. He concentrates hard and then, he hears it. Louder this time, a soft and gentle humming coming from somewhere near him. 

He drops the papers to one side, not bothering with them for the moment because this is more important, because he knows who that voice belongs to but it can’t be!  

He gets out of Castle Byers, looking frantically around, trying to pint point where the voice is coming from. He screams until his voice is hoarse, until he chokes on his own saliva and until his cries come harder than ever before. He slides down on the floor, sobbing and feeling his heart hurt and break and practically stop functioning. He feels numb and scared and lonely. 

But the voice, it’s still there, still humming softly and swirling inside his mind until it’s all he can think about. He hears Will, singing it, as if he was doing it for him, for Mike. As if Will could see he’s there, waiting for him. 

Mike stops crying, though his hiccups take a little longer to halt, and when he’s calmed down, he does it too. 

He starts to hum sweetly to one of Will’s favourite songs of the moment, a song he’d always excitedly talked about, and doesn’t stop until it’s late into the night and he has to go home, leaving a part of himself there, in the place that connects them together. 

(What he doesn’t know, until much later, when Will does come back, is that Will also heard him. Mike’s pleasant and silky singing voice all around him, surrounding Will like a protective cape and bringing him a warm and comfort he hadn’t felt ever since he was taken away. Will had felt his resolve harden and his hopes soar into the sky the moment he’d listened to Mike and it was one of the things that had kept him alive there, in that terrible terrible place.)