So while I was thinking about my story plot I came to question it. The main idea in the story is a conflict involving mages, vampires, and a religious group we will just call them The Order. My idea is that anyone in my verse can learn magic, but it requires access to a certain part of the brain. Most people need to go through a lot of meditation and study to become effective mages, others are born with a certain ability that they identify as some kind of "magic" at some point and look into it further, finding the hidden mage communities. Practitioners of magic are "mages." The Order is a group of pure humans. A few use magic, but decide its a "gift from god" or that they were meant to discover it in order to combat the supernatural horrors of the world. So the Mages have no problem doing magic, and the Order could do magic but most of them won't for religious purposes. Then there are the Vampires. Vampires, along with Demons and Werefolk (in their were form. For example, a werewolf while in wolf form) cannot perform magic. I am trying to think of a reason why that the reader will find acceptable. I wan't to avoid a reason that is too simple. For example, saying simply that mages are mages and vampires are vampires and leaving no reason as to why no vampire ever attempts magic. I thought of the idea that vampires are too focused on their thirst for blood that they cannot achieve a certain mental clarity necessary to learn magic. Now this wont work because my main character is obsessed with bedding as many women as possible, trying every strain of marijuana, and his own ego but is still a mage. There was also an idea that crossed my mind about a certain internal energy humans have which goes away when they are corrupted (for example, turned into a vampire or while in a were form). So this is something I am having trouble with. Can you help me out?