Bah, lost soul's AI could be improved too... so that they don't forget about the player after failing a charge. Current AI is a big improvment over the previous one, but is sometimes extremely annoying, indeed. (especially as vampyre in the lava pits :p)
Why not just make LS keep track of the player after a charge ? At least, until they charge him again. This would make them less predictable (as in Doom, they could wait a lot before charging), and therefore more dangerous than current lost souls.