Prolonged discussion whether it's a gift or a skill. (Skill, please, for my sake. Unless you make it somehow not a way to make your character a special little snowflake. No, persecuting your special little snowflake doesn't administer a cure, it worsens things.)
Two basic structures for a magician in society. They can form an elite and highly regarded layer of soceity. Or they can be the poor perscuted pariahs. The thing is, if you make them just part of society, you have either a comic story, or the background for a thriller like The Dresden Files. The other two forms generate more story ideas that are inherent to them.
Of course, there's also the alternate America with magic -- Robert A. Heinlein's "Magic, Incorporated" or Poul Anderson's Operation Chaos. Both of which feature invasions from other worlds, so to speak. Eruptions, maybe? But you need some conflict, and the setting didn't hold it inherently.
There's also the possibility of having a priest caste with magic, but that was late, with no time to get into it.
Also, this was the panel where a panelist tried, severally times, to stay up in the library allegedly haunted by Archbishop -- Law, I think. They have his heart and his journal. He's supposed to be bad-tempered, and frightens all the servants -- then, he was executed on trumped-up charges.