You know what I think is cool about Cuphead? That you can tell that Cuphead and Mugman have different personalities even though the plot is really simple and they don’t talk much outside of the 5 or so storybook cutscenes.
You can just tell by their body language in their starting animations, equipt cards and in the cut scenes that Cuphead seems to be more reckless, mischievous and forward. And Mugman seems to be more carefree, he likes to have fun too but seems to know when enough is enough.
They could have easily made them similar and just the typical player one player two drones but they didn’t and I just think that’s cool.
This AU is some kind of alternative ending in which the Devil kept the contracts. All the bosses will be taking the Underworld Express at their own time, I don’t think they’ll be dragged to Hell all at once. Considering circuses have a reputation of being unkind, to say the least, to their animals, I saw it a fitting destiny for Grim.