Magic
How it works
There are two types of magic you can have, active or passive: active magic can affect the world around you and is used with potions and blood, passive magic manifests under specific situations and can only affect yourself while everyone has a magic power, its considered on a societal level that a big part of the populance has none, simply because their power is subtle or useless to them or incompatible with their current context.
Magic comes, in the very literal sense, from blood. Human blood, interacting with different factors, is how magic happens, and the amount of magic someone can do is limited by the amount of blood they can take from their own body. Every individual is different, and so every person's blood can do a different, usually very specific, type of magic. For that reason, stealing somebody's blood is one of the highest offences that can be comitted and it is also why some places where a lot of blood has been spilled in the past can change the environment in it. For example, there is a field of flowers, in Liv's kingdom, where some years ago a serial killer buried the bodies, and the bees that take nectar from that field make floating beehives. Those domestic bees belong to an old lady who makes and sells floating candles.
Active magics need a lot of experimentation and study to be used effectively, which not everybody has time for, so even having that kind of magic doesnt guarantee a place in magic user society. This is why most magic users in the alliance are wealthy or have a patronage of some sort. Of course there are exceptions: different guilds regularly test and recruit in towns to find people with magic suited for their guild.