"Paradise? Oh, I've been there, but it's not a place I would stay." The young man stopped what he was doing and walked to the windows, staring out at the road to place his thoughts. "About five miles down the highway between here and there, you hit the threshold. It's this thing that separates everything about this world and that city. There's rules - about crossing it, I mean - but they don't matter much unless you're the sort intent on breaking them."
"The police are a bunch of assholes. Most of them aren't human, and if you see one start telling you to do something on this side of that thing, tell me." The absolute uselessness of telling on a police officer to a gas station clerk was, almost, amusing, but he continued on, dead serious: "There's all kinds in that city: humans, devils, the more... devout. They do business, play along to a set of ever-changing rules, and do their best to see that anything useful falls in their lap."
"...I guess in all reality that makes it not much different than any other city, but when you start to look too hard at the seams, it all falls apart and you can see the evil right in front of you. No sullen metaphor for the human condition: just straight, raw, malicious evil staring out into the streets and waiting for an opportunity to feed."
"I'm just not that interested in the business of killing; things or people."
Paradise City, isn't. It certainy is, in that on some level, it exists, but its relationship with reality is tentative, and which reality, even, is something of an issue. It's no fantastic conflux: it's more like a bog where a number of waters sometimes reach. Nearly all of time's axes don't quite agree when it comes to Paradise, and spatially, it's best described as somewhere in America - or at least, the (primary) currency is American.
Where or when doesn't exactly agree with the space; though it's mostly causal. The city is a conflux which attracts those looking to escape, those looking to hide, and those looking to grow.
It's real enough in the ways in which Paradise is a genuine city; most don't have the time to peer too close to scrutinize. Work, life, and everything else distracts the majority of the human population from anything that isn't close too home, but for the rest, the strange just has a way of poking out of every bush.
As a setting, Paradise City is essentially a modern fantasy setting that's intended mainly for demon hunting types of characters to interact both with each other, their prey, and other factors.
This isn't to say that it's only a thing about demons, angels, and whatever might be killing them; rather, it's that the primary inspiration comes from Devil May Cry and Bayonetta and is taking concepts from the worldbuilding in both series to their logical extents.
Therefore, the setting follows some similar rules as far as certain interactions; however, following up with that, some of the ideas and concepts regarding magic are taken more specifically from Magic the Gathering - and because of their nature, one might even suppose great sorcerors the likes of plainswalkers exist. For clarity's sake, consider this a (currently work-in-progress) story bible to prepare for making a character or for guiding interactions between different entities:
Manifestation: Even the most basic demons and angelic hosts can manipulate the world through different means even if they cannot manifest any form in Paradise; this often means that generic demons who aren't coming straight from hell often have their bodies made up of different, unique materials - sand being a particularly common one - in order to interact with the world at large.
Will: Throwing punches at a demon (angel, or even a hunter) in its true form isn't as effective as one might hope; it's like punching in a dream where when it comes time to strike the target, suddenly there's a wall of water, absorbing the majority of the motion - and impact - before it reaches the target. Will manifests itself largely as the ability to be immovable in the face of an opposing physical or magical force.
Magic: Can be simplified into three categories: Sorceries, which are powerful magics that require certain timing and preparation; Enchantments, magic that is 'permanent' or lasting (rituals, buffs, so on and so forth); and Magical Abilities, which are more the inherent capacities of different entities to perform feats which may be impossible, or to manipulate certain things as if it were natural. Sorceries can be countered, enchantments can be outright destroyed, but basic Magical Ability (for example, Will would fall under this category) cannot be easily or readily swept aside: more often than not, they must be matched.
Soul: Possession of a soul is an important factor in consideration to various magics. A significant portion of the human population of Paradise genuinely lack souls; these individuals are known as Husks, and ostensibly, it is impossible to tell a Husk from an actual person. Accordingly: the soul (or consciousness) can be separate from the body, it can be separated from the body, and it can even be shattered or otherwise manipulated - but quite a number of Husks are simply born rather than stripped of their souls at a later date.
Rite of Conquest: Demons come in a wide variety of explosively evolved varieties. There are many shapes and sizes - some of them which used to be human, some which were once even angels - regardless, all demons are bound by a magic ritual which is referred to as the Rite of Conquest: as one demon's might is proven, to the victor goes not just the victim's life, but their power; however, this enchantment works surprisingly loosely, providing the boon to any victor over a demon, be they one themselves or not. Typically, the most immediate result, is that eventually even a human can manifest Will like a demon or angel can inherently - hence why human hunters can also share the trait.
Rite of Fealty: Angels, conversely, gain greater power by serving their lords and ladies - their gods. There is no direct higher power which holds dominion over Paradise City, but similarly to the Rite of Conquest, the Rite of Fealty is looser in execution: an angel serving another angel, man, or even demon that they have sworn themselves to can draw power from the Will of their lord, as long as they are acting in their best interests. Fallen angels are not necessarily true demons, though they can be their progenitors, but they are angels fallen from the grace of their master. Both the Rite of Conquest and the Right of Fealty are esoteric enchantments which exist and bind all who use them, they cannot be formally targeted by any standard sorcery.
Rite of Blood: Blood, and the spilling of it, is a powerful magical catalyst. Whose blood, what blood, a number of important considerations can be used in sacrifice for magical power. Blood mages of a high enough order engage in the Rite of Blood, stopping their aging and granting similar power as of the above rites with but one catch: participants must drink blood to sustain their magical capabilities.
The Devil: Due to the nature of demons and their constant bids for power, the ruling demon of hell, the Devil, is not a position which any one demon can maintain indefinitely. There are a number of greater demons vying the position at any point in time, either through direct or indirect means.
Outsiders: Individuals who do not pass through the threshold which separates Paradise City and the surrounding counties from the rest of its reality but do enter the city from other realities besides hell or heaven are marked as Outsiders, and as a general rule, they are significant threats.
There are three main archetypes of mercenaries in Paradise: Hunters, Stalkers, and Sweepers. Each of these three archetypes are orientated towards different sorts of missions and represent dynamic layers. Typically speaking, most mild-powered characters would fall under the category of hunters for reasons that will be explained shortly.
Hunters: Hunters are individuals who are capable of fighting a wide variety of the fantastic threats which are contained in Paradise on near or equal terms. As this is beyond the capacity of a normal human being in most respects, they usually are assisted by some magical ability - or aren't quite human themselves. Everyone needs to get paid, after all.
Stalkers: By contrast, stalkers are something of a middle-ground: usually by focusing on infiltration, ambush, and exfiltration, they gather intelligence and determine what targets are worth pursuing; backing off if a target is beyond them or tackling the matter at hand if its within their capabilities. Ninjas, special forces, sometimes shock troops even.
Sweepers: Few problems can't be solved by firepower, except perhaps, the problem of collateral damage. Sweepers are the grunts who focus on using every resource available to them (read: guns, explosives, and/or flamethrowers) to eliminate threats to Paradise City. They are, remarkably, the least eccentric sort of mercenary Paradise has to offer, but that doesn't mean they don't have their place and value.
Paradise Police Department: A group of monstrous individuals who take on the burden of policing the city. In large part, for the majority of the human population, the police seem remarkably benign; often not dealing with 'petty' crimes unless absolutely necessary. Their real functionality is to keep the majority of the demonic population under their heel and under control. The police chief herself keeps her men in line. A demon of a particularly high order of strength and caliber, enough to rival any would-be Devils seeking to establish a claim in the city.
The Hotel: The Switzerland of magical items. Most legitimately obtained or possessed magical items of worth are stored by the Hotel at one point or another and protected by a wide array of incredibly skilled guards. From the desk man, to the penthouse, there are frighteningly capable men and women on every floor, each prepared to lay down their lives in protection of the most precious examples of artifice, but its guests can (and often do) include living entities.
The Conglomerate: It isn’t really a single entity, so much as a collective of companies. However, it’s certainly all stirred by one hand, and the denizens of Paradise City just refer to it as The Conglomerate. This is where technology rivals magic, and money is power in the regular world. That usually doesn’t amount to much in Paradise City, but it manages to catch up when we’re talking about a lot of money. Black suits, black ties, and sunglasses, oh dear.
Shooters and Shenanigans: An unorginally named mercenary dive bar, and also, the primary recruitment location for the majority of low level or neutrally aligned devil hunters, mercenaries, and even halo hunters. A number of handlers make it their base of operations. You might get kicked out, but they'll probably let you back in. When the heat dies down - and, yes, they did just let that combat schoolgirl in without flinching.
Jack's: As simple as it isn't - the watering hole of Paradise City's elite mercenaries and big players, the bar matches its owner: quaint, friendly, dangerous. It is, however, the safest place to be in Paradise City, as long as you abide by one simple rule: business is handled off the property. And Tuesday is chili night.
Which Book?: A witch-owned bookstore which specializes primarily in information and spell books when it comes to the general populace, but also, a source of artifacts and other magical items (mostly) for witches and warlocks, and other things related to summoning and binding. They do not, officially, endorse summoning anything in (the city limits) of Paradise, but there is an associated coven ran by the owner.
Paradise Central Station: No one rides the subway in Paradise City, not if they know any better. Even the monsters hiding among men dread the place: it has routes which run deep into the earth, and while the schedule is always kept, it is a cruel, dark place.