This question already has an answer here:
I downvoted someone, and then they got angry with me, so they downvoted me within 2 minutes. They were all random questions (I think actually my top 9 questions). They got reversed. No matter, downvoted again yesterday. Reversed. And nope, still downvoting me. Proof:
Now, I have a feeling this guy isn't going to give up for quite a while.
I've seen all the posts on serial downvotes, but this is persistent, and I don't think it has been covered before.
Can anyone help me on what to do?