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It is an unspoken rule that if Namjoon has shut himself in a studio, he will open the door once appropriate, and noone is to disturb him.
Sometimes, Namjoon needs to be in his own head, needs to reorganizes and re-prioritize. It comes, suddenly, without notice. And it is what keeps Namjoon going, keeping him from breaking down and losing himself, so he accepts it.
The door closes, Hoseok's eyes will stay on it for a while but will eventually leave, Taehyung will knock after a few hours and if he does not receive a reply, he will leave Namjoon be. They understand, in the same way they understand sometimes Jimin doesn't want to stay up all night dancing but need to, sometimes Jungkook will stutter and they need to guide him back to words instead of letting Jungkook lose his coherency further to anxiety.
It is hard to learn for Seokjin. Hoseok tries to tell him that they should be alone sometimes, that the unit that is them can take a break for one second and their existence is not erased because of the fact that Hoseok himself has not talked to them in a day, or Yoongi hasn't made another song but has been writing lyrics for things he will eventually scrap. But they ultimately don't blame him, because he cares too much and thinks they are fixable, in the way he can fix an under-cooked steak or a whobbly table. And of course, even if he doesn't understand, he respects that this has become the way they do things.
Seokjin learns to not open a door Namjoon has closed, an invisible barrier between him and the galaxy that is his leader. Instead, he sits by the door and do his own thinking. Sometimes, he repeats his life motto to himself, a string of words noone would understand but him, and finds himself cataloguing his emotions in neat little boxes. He doesn't need it, he has always been good at dealing with his emotions and staying truthful to himself and not losing, never losing his liveliness. But he falls in love with Namjoon this way, pressed against the wall of Namjoon's world, toeing the boundary. The connection is established through their share time (though it's considered shared by Seokjin only) and it lingers long past that. Seokjin learns to understand Namjoon, in the way he now understands hiphop and dance and the stage light. So it's time well spent.
He never understands fully, of course, but it doesn't matter anyway. Not when Namjoon opens the door and the first thing he sees is Seokjin and the first thing he hears is.
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