Bee is really the most evil, when you think about it - written by a Mammon kinnie
Now, I know this is gonna read like me being a Mammon apologist (because I am) but this is something I've been meaning to bring to light for a while now. I believe that Beelzebub is the most evil Sin, at least of the ones we've seen so far.
Bee might seem very approachable and friendly, but this is exactly what makes that much worse than she otherwise would be.
The main thing here is the hellhound pound system, which is, at least in my eyes, the most horrific piece of worldbuilding we've gotten in the series. An entire sentient species being treated like pets and kept in squalled conditions within a framework created and overseen by their ruler and likely creator, someone who is for all intents and purposes, their god.
Thought not confirmed, it's implied hounds that age out of the system are just straight up euthanized. Again, this has yet to be confirmed, but it definitely doesn't help Beelze's case.
And what exactly becomes of Gluttony-born hellhounds who survive the pounds and get adopted? Why their love bombed with parties where their "benevolent" mistress uses their positive emotions to make a substance that can form dependency in demons the way alcohol can in humans just so she's even better off. Either that or they end up adopted by someone who just uses them as expendable muscle.
At this point I'm sure someone is saying that Mammon is still worse, and they'll likely point to the general state of Greed, being a polluted over-industrialized mess. But this just raises another point in my favor.
Unlike Mammon, who's upfront about only caring about his citizens' money, Bee puts on the persona of being a ruler of the people, not above them. She makes Gluttony seem so idyllic while also basing a contender for Hell's most deplorable enterprise out of it.
Beelzebub is such an adept manipulator that she gets Loona to come out of her shell, when Loona's closed of nature was spawned from her trauma that Bee's pounds are responsible for in the first place! For all we know, this also applies to Vortex, I mean, something had to blind him in one eye, perhaps a fight with a former cellmate?
And worst of all, she herself doesn't seem consciously aware of it, she may genuinely see nothing wrong with the conditions her subjects live in, likely because she judges their quality of life based on their "vibes" at her parties.
I just want to end this saying that I don't hate Bee, nor do I think Vivienne intended for people to infer these things, knowing her, it's likely she just didn't fully consider the implications while writing. But it is still a valid interpretation of Beelzebub's character based on what we presently know about her.