So I made a correlation between Will and Holly and what intrigues me the most is that the two of them were depicted as wearing necklaces.
They both went missing at the hands of interdimensional forces and wore necklaces that inspired them to be brave. Who was that figure that inspired both of them to be brave? Mike Wheeler!
Mike was the one to give Holly her necklace of Holly the Heroic, a cleric who can cast dimension door. Mike called Will a sorcerer and believed in the innate nature of Will's powers.
Mike referred to his D&D character as Mike the Brave, someone who never gets scared. Who fights sorcerers and monsters. We see Mike step back into the leader role and he was at the forefront coming up with plans such as the turnbow trap. This happens while Holly is taken and El is in the Upside Down, allowing his true personality to come back. He is someone who isn't expected to show fear so what does he do - he passes on his brave traits to Will and Holly.
Mike is the reason Will unlocks his powers and as a result he was able to find freedom and acceptance in himself. He inspired Holly to be brave and to fight back rather than just standing there and that helped her live up to her heroic name.
Mike may have been the one to give Will the necklace after all during the two year time jump before the epliogue just like he did for Holly to remind him of what he went through and overcame.
I can't really make out what Will's necklace is supposed to represent but it could very well resemble a cleric's sigil or at least a mage sigil which wizards like Will use to mark their possessions and cast symbol spells.
The necklaces are worn around their necks to protect them from the monsters. Wearing these necklaces allows them to exhibit their bravest traits.
Holly wears hers throughout the entire season until it is broken when the other children attack her and in the end, she ends up finding that bravery within herself instead.
Will only starts wearing his in the epliogue. We only see it being worn during the D&D scene but we don't see him wear it in the future Mike envisions for Will when he meets up with his epilogue boyfriend.
Will has found acceptance in himself for who he is and despite this, he hasn't fully taken off the necklace. This shows that he has allowed himself to be brave. He hasn't taken off the necklace because Mike himself isn't ready to be brave. He hasn't found that bravery within himself yet.
This is reflected in the way that he influences the party's futures knowing he won't get a future of his own. He influences Will's future by giving him an imaginary boyfriend.
A boyfriend that isn't him. He is giving up on a future he couldn't have with Will because he gave his own bravery to Will and he was able to accept himself when Mike never did. When Will walks away and Mike seemingly grazes his D&D book with his hand, that is when he accepts the finality of the situation that he could never have Will. That he can never accept himself and be brave because he didn't think he deserved it. He gave himself the ending he thinks he deserves because he watched El die in front of him and this happened all because he couldn't accept himself.
Mike's best traits are reflected in Will and Holly because they get to live out his hidden fears and be brave enough to accept themselves, something he never got to be because he was too afraid.
We see at the end as Mike sees Holly and her friends embark on their own D&D campaign. Holly is inserted into Mike's role as the dungeon master. She gets to be the brave one now. She gets to be the leader. A person Mike wished he could have been and now Holly gets to step into that role.
Mike's best traits and mistakes are reflected in the narrative and that is what allows him to influence it. To give others happy endings when he couldn't have them himself. To allow others to be brave and to accept themselves for who they are when Mike never could.
Hopper had given him two roads for him to go on with his life and this is the role he had chosen. He doesn't want what happened to El to happen to anyone else and his influence over his friend's happy endings is what costs him his own happiness. He put others before himself and gave them the brave he never got the chance to exhibit.
Mike is the dungeon master. The storyteller. The leader of the party. Everything leads back to him. The tragedy of the story is that Mike never got to accept himself and it just played out before our very eyes. Mike is the heart that ties everything together. The whole narrative is dependent on him and the silent struggles he passes on to others. That is the tragedy of it all and in this case, it is the tragic end of Mike Wheeler's story.
