There is a daily/nightly script to correct 'chain hate downvote pattern'. I propose to punish the 'hater' by taking the amount of reputation points from his/her account that he/she removed from the victim.
Feedback. The victim should be notified (inbox) that the script has been run, and the "hater" should be notified as well. The victim should not be informed as to the identity of the "hater" of course.
Maybe a moderator should be notified as well to take additional action against the "hater", or not? Edit Maybe a day in the penalty box?
P.S. I've had a bout of downvotes, but nothing serious.
P.P.S I've not suffered this problem myself.
P.P.P.S As 'gnat' noticed, this is about feedback.
Edit Funny that proposals against downvoting get seriously downvoted.