So Elva's just been storing up ammunition for the empathy spell without knowing or wanting to. Which is also horrible.

The worst part about it is, Elva doesn't just feel people's actual pain. She feels their potential pain. And before the spell got "fixed" in Brisingr, it directly caused her pain if she tried to ignore said potential pains. It's like exponentiating pain.

I don't think you're going to hit Eragon with the empathy spell, though. I think Eragon's going to use it against Vanora, and it's going to make her stronger instead of weaker.

In the words of Christopher Paolini, "no comment." ;)