Thank you for the ask!
My ship playlist for him is decently long, but for one just about him?
I’d have to say my top to are ‘Rocky Mountain High’ -John Denver + ‘Collapse of the Kola Superdeep Borehole Tower’ -The Mountain Goats
RMH is a song about experiencing nature and falling in love with it – this is actually something very important to BJ! He canonically buys up islands to preserve their natural habitats. He loves wild animals, and while he doesn’t have many friends, he cherishes those he *does* have very much.
Borehole Tower is much more introspective. It’s a song about pushing forward, about continuing on despite the danger, and being humble and discreet about it. It’s a bit hard to explain if you’re unfamiliar with the manga, but Jack never gets a big head about what he does, and it also often leads him into extreme danger.
The manga often becomes very melancholy, striking a fantastic balance between pessimism and optimism, which reflects in the lyrics of the song.
These lyrics especially hit for me