I find it interesting that you seem to assume Eragon is going to get hit with the Empathy Spell. I won't confirm or deny that, but I will say that I sort of have a different interpretation of Eragon than just saying he's a sociopath with zero empathy.

Rather, I think Eragon is someone who started as a relatively normal person, albeit with some glaring character flaws, and has since badly lost his way because he never learned to question himself, only to justify. In Eragon, there are several moments where he has genuinely heroic instincts. One scene I particularly remember is the slave auction in Dras-Leona, where his immediate first instinct is to use his magic to free the man currently on the block, and he only stops himself because he realizes it probably wouldn't work and would only put him in danger too. In that moment, he wants to help someone but feels genuinely powerless to do so and it's deeply frustrating to him.

Compare that to the Eragon in later books, and it's clear that Eragon has developed as a character... but in the wrong direction. He's learned to shut away his empathy and justify whatever needs to be done in the name of his goal, which he's also done some heavy mental gymnastics to justify to himself. There's something really tragic about that, in my eyes.