RETCON NOTE: This post replaces portions of "Mages of Monvesia;" see also "Mages of Monvesia - Scholars."Mastery of the arcane arts can be achieved by strengthening one's connection to the Spheres of Power. This can be approached through formal study (see scholars), or else through otherworldy pacts or natural power. The latter typically exist outside of "accepted" society, and are therefore called malefactors--commonly understood as "evil-doers," though originally meant to mean "incorrect doers." There is nothing inherently evil about the sorcerer or warlock.
Enhancements to the class features of both these classes can be found in Unearthed Arcana.
Sorcerer
Different races have their own traditions "explaining" the nature of sorcerers. To an extent, each version of the sorcerer story is true. That is, these different versions of what a sorcerer is represent the sorcerous origins common to that race's history.According to the omnipresent Senarian churches of the humans in Prace, sorcerers are possessed of an inborn connection to one of the Spheres. While all adherents of the elemental philosophies believe that every being has such a connection, it is the sorcerers who have accepted it and gained power from it. A sorcerer's elemental connection may be tied to his or her race (or culture, if human), personal philosophy/temperament, season of birth, etc.--but it does not define every aspect of the character. Two origins reflect this: Shadow Magic (Xanathar's Guide) and Storm Sorcery (Sword Coast or Xanathar's Guide).
Until such time as other, official origins are introduced, these two can be used to mimick the other elements. Use Shadow Magic for Light Magic: reversing references to necrotic and radiant damage as well as darkness and light. Use Storm Sorcery for other primal elements, such as Flood, Quake, and Wildfire Sorcery: use alternate damage types and movement speeds as appropriate.
Among the successors races of the Empire of the Morning and Evening Star, it is said that sorcery is the result of having had a Dragon Ancestor. This connection is not necessarily one of direct ancestry, but could represent a bloodline having been favored by one of the dragon lords of old.
Remember, there are only six types of dragons in Monvesia--each associated with one of the elemental forces of one of the Spheres. Therefore, this is one origin that also follows the Temperamental beliefs of the Senarian churches. (An early version of 5th Edition Monvesia used a variation on the Dragon Ancestor to represent Elemental Magic).In the land of Desolation in Raviq, the HMDJVNW have taken control and cursed the native races into submission with a psychosomatic ailment known as Taint. This cure is so potent in Desolation, that even the land, the neighboring Frenetic Ocean, and magic itself have become warped. Some who have been affected by the Taint have also gained a connection to the Wild Magic that was released into the world because of it.