I'm not saying I need a Devil Went Down To Georgia style duel between Johann and Kravitz/Lup. Either Lup or Krav is the devil with the other two reapers as their musical backup. Either it's a fucking au where no one dies and there's some kind of Talent Show but like Intense at the BoB base or Kravitz made a deal to let Johann's soul go into one of Lucas' robots
OHHHH BOY, you have hit directly on one of my interests! I really like the idea of Johann striking an unusual deal with Kravitz or Lup for his soul, it seems to fit his character even…
Okay wait hold on I had an idea. If it’s Kravitz that he has the duel with, it doesn’t even need to be an au. Maybe this has already happened - imagine years ago, when Johann was younger and already a prodigy at his art. He loves to play, he hates being told what to play, and he has a bright future ahead of him. But there’s a war - there’s a lot of wars. And every reaper is needed to keep up with the casualties.
Johann’s town is hit - not by a relic, but by the suspicion that someone in town has one - and there are few survivors. Johann is not supposed to be one, but when Kravitz finds him, he’s still holding his violin, miraculously unscathed. Kravitz comments on it and his own history with music, because he’s not used to this, he’s not used to collecting souls that don’t have to be chased down. Johann has an idea. He wants to play one more time, and if he can play better than Kravitz, then he has beaten Kravitz in competition and wins more time. And Kravitz, who needs a bright moment in the middle of all of this darkness, agrees.
As soon as Johann starts to play, Kravitz knows he’s beaten. They play a duet instead, and Johann survives the night. He doesn’t remember the wars, eventually, but he vaguely remembers the sound of two violins playing together.
When they meet again years later, Johann grins a bit and says that he didn’t get much more time after all. Kravitz smiles and replies that Johann had just enough time for everyone to remember his name.
(The intense talent show idea is also quality, but I imagine even after Johann dies there are talent shows. At the very least, Johann and Lup have duels on various instruments in their free time all the time. It’s a thing. It’s a great thing.)