The first thing you need to know about magic is that everyone has at least a little.
The first thing you need to know about Percival is that his magic comes out when he talks about what he wants.
The second thing you need to know about Percival is that he doesn't talk much.
The second thing you need to know about magic is that although trained mages almost always use spells to increase their power, natural magic can come out in any number of ways.
The first thing you need to know about Leon is that his magic comes out when he sings.
The second thing you need to know about Leon is that he's been telling everyone for years that his singing voice sounds like a cat shrieking.
This is actually true. There's a reason no one knew about his ability even before the Purge. Magical talent and musical talent don't always go together.
The third thing you need to know about magic is that not everyone realizes they have it.
The first thing you need to understand about Gwen is that for most of her life, she was far too poor to afford mirrors, so she genuinely doesn't realize that her eyes glow when she sews. This doesn't stop her from always sewing hunched over because part of her knows she's safer if no one can see her eyes.
The second thing you need to know about Gwen is that after she marries Arthur, she doesn't sew as much anymore.
The fourth thing you need to know about magic is that it can be suppressed.
The first thing you need to know about Gwaine is that he can make things explode with his mind. This is not as useful as he once thought it would be, namely because Gwaine is not stupid, and he knows that if he goes around doing this, eventually he's going to get caught.
The second thing you need to know is that Gwaine is terrified of dying like his sister did - namely, tied to a stake.
The third thing you need to know about Gwaine is that he started drinking in an attempt to get rid of the dreams that came when he didn't use magic. Eventually he realized drinking made the urge to use magic go away for as long as the buzz lasted.
Unfortunately the effectiveness of that remedy fades over time. Gwaine realized it shortly before he joined in a bar fight he never dreamed he could win.
The thing that no one talks about regarding magic, but that is far more important than any of the other details, is that not using magic drives people mad.
What you already know about Uther is that once his wife died, he refused to have anything to do with magic, including his own.
What you already know about Uther is that eventually, this had a cost.
The other thing about magic that no one in Camelot talks about is that not all magic can be helped.
The dreams started for Arthur at about the same as they did for Morgana. Unlike Morgana, he didn't go to Gaius with them. He was the heir to the kingdom. He couldn't be seen running off in hysterics just because he had a few bad dreams.
No matter how bad they got.
He realizes that the dreams are visions eventually which means he has magic, and as everyone knows, magic is evil, so he is evil.
He doesn't dare trust himself after that.
The thing that no one was ever sure about, not even Gaius, was how, exactly, this affected Emrys.
Hunith believed that since the magic was so strong in her boy he was driven to use it more frequently than most, and Gaius had to admit, that might be true. That might be why he was so reckless with it.
The dragon believed Merlin was magic itself which would mean that instead of his magic pushing him to the brink, he was pushing the boundaries to get attention and ignoring him was never exactly safe.
Gaius's magic certainly got more . . . demanding once Merlin came.
The last thing you need to know about magic is that despite all of this, no one who had tasted it could quite keep from loving it, no matter what else it did.
