I'd disagree on too much worldbuilding detracting from the story, or doing the minimum amount of background work to get the story working. Worldbuilding can become a problem if it prevents you from writing, sure, but if you do it right, it makes the story much richer and original. If you mean that it's problematic to include too much worldbuilding, then that's a writing problem, not a worldbuilding one; a good writer should know when to stop expositing.
Worldbuilding as you write can work, just like any other kind of pantsing, but that depends on what kind of writer you are. If you're an outliner, or you're stuck at scenes because you don't know how the magic should work there, pantsing won't be easy.
But the worldbuilding here looks like it'd be very relevant to the story.
Although, if you're not having fun worldbuilding, that could be indicative of other problems.
In my world, you need to have "something else" in your blood to be a magical being, and, if you have this "something else", you aren't human. The symbols aren't necessarily magical themselves, but they indicate alignment. For example, in one scene a character shows a medal to a guard which contains the symbol of the demon he serves, and is granted pass.
Er, for this process to work, you have to be able to list pretty much everything you know about the story and the world. You don't have to do it here, or even physically (although I find it easier), but every idea you have about the magic system is important. This includes all the images in your head and all the ideas you have. The specific questions I asked are less important than the process. The process is basically 1) ask questions, 2) answer them; the
what do you have? and
what do you want? are to collect information for 0) have things to ask questions about.
Like, that one scene you have where a character shows a medal and is granted pass? That's an entry under
what do you have?. You need more stuff like that. Because that scene has implications - what you want to do is explore those implications. Your magic and mythology also has to accommodate those scenes.
First of all, is this an original world or is it urban fantasy-esque? I get the impression of the latter - though demons may have an original world that you may or may not be interested in fleshing out. The worldbuilding elements with your demons and vampires are equivalent to your mythology, I assume. There is a
masquerade. Correct?
Right, so you have this "something else" in your blood that makes you both magical and nonhuman. Let's skip to step three for a bit. I'm making some assumptions since it sounds like it's humans (and maybe other animals?), but with an extra ingredient that makes them not considered human, instead of magical creatures just being creatures and happen to not be human. (You don't have to answer all the questions; they're springboards for your ideas. Also, not a comprehensive list; it's ideal if you can come up with your own questions to answer.)
- Having this magical thing means you're not human. What does this mean? Is it just a cultural thing, and you're not considered a human being because you have this thing and humans don't? Or is it literally true?
- Do people consider being human a good thing, so humans are higher-status than magical beings?
- Is it genetic (or at least passed down from parent to child)? If so, are "half-bloods" a thing? physically, as in the magic dilutes over generations? culturally, as in you're considered less [magic thing]/more human if you have human parents? For that matter, can normal humans (or the mundane version of the magical thing) and magical things interbreed?
- Is it contagious, like werewolves and vampires? If so, how?
- If it's "in your blood", can others use your blood to get it? If so, how?
- Is it possible to lose your magic? What happens to you, if so?
- Are there different kinds of magic that can be in your blood? If yes, do they interact? If yes, how are these things different? ("No" would be something like Harry Potter's witches and wizards - you're magical or you're not, period.)
- What powers do magical people have?
- Do you still look human? Is a magical person essentially "human, but with magic" or are they physically changed to an obvious extent?
- Are there any advantages to not having magic/disadvantages to having magic (e.g. werewolves vulnerable to silver)?
- etc
- er, actually, are these separate from the demons and vampires mentioned below?
Other things, just from you having magic.
- What does magic do? What are the effects in can have?
- What do people have to do in order to use magic? What objects do they need?
- How does the magic work?
I want it for things to make sense in my world. I don't want someone to read my story, spot a scene then say "how did he pull this off, it makes no sense!". It might not be needed as long as the plot itself makes sense, though.
But that's not the only thing you want, right? Okay, so I explained badly - mostly, these are very specific things and tied rather tightly to the first question (although it's still valuable to know that the magic making sense matters to you). Do you know your plot? There will be events happening in your plot, and for those events to happen, you'll need something to be true.
For example, you have a scene where someone flashes a medal with a symbol and a guard recognises it. For this to be the case, naturally, you need the symbols to be well-known, but not necessarily magical; you need the symbols to be respected, so they need power behind them; you need the symbols to be trusted, so either it's hard to fake or no one dares; etc.
The idea is that, in a modern setting, people are oblivious about demons, and then the demons use humans to get what they want, which is power. In my story, demons seek only power, for no specific reason, and they feed on evildoing, like classic demons.
Demons originated from evil caused by humans, and split into two main categories: vampires and demons proper. The demons were banished from this realm, although their existence remained through forbidden crossbreeds with humans. Vampires are more civilized than demons.
Okay, so if you're taking from classic demons and also have vampires, you can take ideas from existing mythologies. You can research what people thought about demons and vampires and pick out the stuff you like.
Anyway, "demons seek only power, for no specific reason" is a perfect place to start working. "No specific reason" is something you can get away with for demons, sure, but why do that. Give them a reason. What do they use this power for? If a demon was the most powerful thing ever, what would it do? Having enemies and wanting to defend yourself or destroy them is a reason to collect power. Having been banished and wanting to unbanish yourself could be a reason. Being terrified that everything wants to destroy you and wanting some security is a reason.
What are the differences between demons and vampires? What are the similarities? How do vampires and demons interact?
How do the demons use humans to get power, exactly? Is it just feeding on evildoing, or something more specific? What is this power (more magical power, more political power amongst demons, etc)?
And you've got evil being a literal, tangible thing here. It would help you if you can define what makes evil in your 'verse. For example, emotions: sadism, suffering, hatred, anger, despair, guilt. Or actions are objectively evil and context doesn't matter: rape, torture, murder, theft, destruction of property, breaking laws (regardless of justification). Or vices: greed, pride, envy, wrath, lust, gluttony, sloth, if you want to take from existing mythologies. Or do you have something like a god that determines the rules, and disobeying the rules is evil?
Also, how do the demons feed on it? Is it enough for the evil to just be there, or does the demon have to be present to harvest/eat/whatever it?
Magical things exist, but the regular person doesn't see them, just that a child occasionally disappears or a pair of lovers are horrifically murdered every so often?
I bolded what I wanted in my story.
The trope page can guide you on masquerades better than I can - see the link above.
The idea of creation is difficult for me because I tend to model my ideas on something that already exists. Creating something "from scratch" is something that burns out my mind, lol.
Let me give you an example. When I was around 15, I played lots of sports games and I "created" a "country" in Northern Europe with its national football team and national clubs. The country consisted of a clash between Swedish, German and Polish cultures, and the names of the players were related to it. But in this case, creating names was something "easier" because, even without knowledge of these cultures, I could just slam something together that sounded good and convincing.
In my story, the symbols are from a brotherhood of three archdemons, each having a domain in the place-that-is-hell-but-named-differently, so they indicate alignment.
The whole process is basically you not having to make stuff from scratch. It's you taking the stuff you've got and building on it.
You can take existing sources for your story, still, but that means research. I've mentioned researching demons and vampires, I believe. You're already taking stuff from Christian or Christian-influenced ideas, so you can go further by using that mythology as a source.
I also hate naming things, which is why I gave those other suggestions. You can actually use a foreign language to various extents (if it's urban fantasy, I guess Latin or Ancient Greek are traditional - this is somewhat risky though), use just the phonology of a language, or use English with some hand wave-y explanation.
For your symbols - what's important to your demons? You could take images from whatever history your world has, or symbols from existing cultures if it's urban fantasy set in this world. Power is important, so you can think of things that express power. Powerful animals, weapons, a closed fist, fangs, whatever. Or if your demons have a history, you can have something that means power but the average reader wouldn't see how it means power without context - if a crucifix implies power to a demon because of historical things with the church and whatnot, the most powerful demons might actually use it, if said demon isn't harmed in doing so; alternatively, people would initially be ??? at it and then a demon grumbles and explains how it's a torturous death and that's totally up their alley.