This is a bit off-topic, but this thought has crossed my mind a few times while reading this thread:
How would you go about redeeming characters that commit the most heinous of crimes in this show? And I'm mostly referring to crimes that the Fandom would absolutely throw a fit over if the show even attempted to redeem said Sinner (ex: pedophiles, dictators, cult leaders, rapists, slave owners, etc.). Of course, Viv would never do this because she is "safe edgy", but I was curious to know how you all would go about it.
Dictator/cult leader/slave owner you could potentially do, depending on how bad their actual acts were. If we're talking fictionalized versions, you could definitely tone it down or set it against a backdrop where it isn't that bad in comparison. Like, a dictator who more or less inherited the role in a dystopian setting where everything sucks, loses power, then realizes the error of their ways and dedicates the rest of their life to making it better. Maybe heroically sacrifices themselves at the end to do something that makes the world less dystopian.
Slave owner is probably the easier one, especially if it's a younger character and the story is about them learning why slavery is wrong and as they grow up, they fight for change. Again, also works better in a fictionalized setting.
I think it basically boils down to:
As sympathetic of a backstory as possible. Victim of abuse, someone indoctrinated to go down whatever path they went, tried to get out of it because they fell in love only to have that love weaponized against them etc.
Have them lose everything, realize the error of their ways, then get dragged through the mud the rest of the story while doing everything they can to undo their previous crimes/make the world a better place. Pitting them against someone who is way worse than them also helps
If they still feel unsympathetic, sacrifice them at the end and hope that's enough.
But if we're talking more like...real world examples, that's a lot harder. It's not impossible for some of those groups, but not something I'd really want to set out to do. With rapists and pedos, I don't know if there's really a world anyone could pull off a convincing redemption story for them.
But in terms of like, the Hazbin setting...I actually think Viv was right not to try and redeem those types of people. Or even focusing on them at all. What was wrong was the baffling world building that they're apparently so evil, Hell just erases their souls entirely instead of punishing them, which, you know, is supposed to be the whole point of Hell. If I was writing the show, I'd use an alias because I wouldn't want my name associated with it at all and I'd probably resort to heavy drinking to justify sticking around for the paycheck.
But after that, I'd include a throwaway line about people like that being in the darkest pits of hell or something, maybe even say the "saveable" souls shouldn't be in the same place as those monsters. Could even have an episode where someone tries to break Charlie's spirits by convincing someone like that to go to the hotel and be completely irredeemable, but then have Vaggie or Husk or someone who is arguably more practical basically teach her not everyone can be saved/don't focus on her failures/don't put all this time and energy into someone who can't be helped when she could instead be focusing on the ones who can/want to be saved. Maybe even have Charlie flip it around as an argument later on, where she admits to the angels she knows not everyone can be saved and she's not proposing just sending everyone up to heaven, but then pointing out is it really fair to have someone whose only crime is being a drug addict suffering the same eternal punishment as someone who lusted after kids.