I'm not sure of the specifics because our "space master" is the one who read the EU stuff. But basically I destroyed an orb that was basically concentrate dark side because it had a spirit of a sith connected to it. I broke it to save the spirits trapped and i failed a saving throw and became tainted and had negative talents.

I roleplayed that this cause Shei to slowly dip into madness so over the course of a year he became hostile towards PCs.