Sorcery and GURPS are apparently on my mind and shit.
One of the aspects of my background material is that the Fallen, the Vyanth, and the Uncout have developed specific traditions of sorcery designed to make their castings more reliable. The basic rules of sorcery and spellcasting and misfires in GURPS and Pathfinder Hekinoe represent thousands of years of sorcerous research and testing and mutation and derping to make the chaotic energies of sorcery more reliable.
So how do we show the special techniques of the Fallen, Uncout and Vyanth? My thought is with Unusual Backgrounds. Here goes.
Unusual Background: Fallen Trained Sorcerer 
Requirement: Will 12+, convince a Fallen sorcerer to spend time teaching you (the process of being taught these mental techniques counts as teaching for the purposes of gaining character points through teaching and practice).
The Fallen of the Necropolis are an ancient race of undead Elduman that have long attempted to be a safe and conscientious as possible with the potent energies of sorcery. Their practices require a still mind, capable of cold logic and iron hard control in the heat of battle and tense situations.
Effect: You may buy off the Radically Unstable Sorcery limitation to your Sorcery. If you do so, the effect of Extremely High Sorcerous Energy areas is reduced to the first tier of Radically Unstable Sorcery, and allows for a check to recover from the failure.
Unusual Background: Uncout Trained Sorcerer 
Requirement: Convince a shaman of the Uncout of The Beast Lands to spend time teaching you (the process of being taught these tricks and tips counts as teaching for the purposes of gaining character points through study or practice).
The teachings of the shamans among the Uncout consist of an ancient oral tradition of tips and tricks to maintain their spells and reduce the dangers of sorcery to themselves, and the clans under their care.
Effect: You may buy the Experienced Sorcerer advantage, even if you do not meet the other requirements of that advantage.
This one requires me to make an advantage:
Experienced Sorcerer 
Requirement: Magery 4+
Effect: You increase the level of Sorcerous Unreliability you roll against when casting spells by 1 (making it a base of 14 in The Known World).
Unusual Background: Vyanth Trained Sorcerer 
Requirement: Convince a Vyanth sorcerer to spend time teaching you (the process of being taught counts as teaching for the purposes of gaining character points through study or practice).
The sorcerers of Vyanthnem are a bold lot, refusing to quail before the risks of sorcery. They believe that fearing sorcery or concerning oneself with the disastrous consequence of it slipping from a sorcerer's control weaken the will and resolve of sorcerers, allowing sorcery to more easily fling off their control.
Effect: You may purchase the Bold Sorcerer advantage, even if you do not meet the other requirements of that advantage.
Again with the advantages. Sigh.
Bold Sorcerer 
Requirement: Magery 1+, Daredevil advantage or Overconfidence disadvantage.
Effect: Increase the number of energy that causes a decrease in the reliability level of a spell by 1 (it takes three energy beyond the minimum necessary to cast a spell to accrue a -1 to the level of unreliability in The Known World).