While he will do many things for money, dying is not one of them. Jungkook came to Seokjin with an off-hand comment how a friend of his is looking for models. In hindsight, Seokjin should've asked for clarification.
Texts and agreements later, he's topless in a little studio that smells like rubbing alcohol and commercial deodorizer with photos of disembodied anatomy hanging from the ceiling while Jungkook's friend squirts paint onto a palette.
Jimin is on his way to becoming a professional body painter. So he says. Seokjin didn't know that was even a thing. He assumed it was like a side hobby of the people he's seen at festivals and events.
As nice as Jimin is—and he's very sweet; he even giggles—Seokjin doesn't much like awkward silence, so he chatters about the shows he's watching, dogs he's met, clothes he's interested in...
And Jimin listens. He makes a comment now and then, usually agreeing with Seokjin or urging him to 'buy that sweater!' or 'pet that dog!'. Otherwise, he apologizes for the coldness of the paint or whines when a glob falls off his brush before he reaches his moving canvas.
Seokjin does his best to sit still, but it's only a skill he can execute when engrossed in a show or movie. He looks out the window across from him, spotting a neighbor arranging a bouquet. The yellow curtains flutter with a gust of wind, and Seokjin reaches out to try and catch its hem but misses.
Behind him, Jimin laughs and puts a hand on a bare spot of Seokjin's shoulder. They're not so far that he needs an aid in keeping his balance, but Seokjin doesn't comment on it. Jimin has small, warm hands and noticeable calluses on his fingers.
If this is how he goes, then so be it.