Its curious that Nidhogg really wants his eye back. Obviously it is his eye but it sounds like its more than just that.

The DRG quest made me think that Thordin might not have been too bad. I still don't think this is a simple one sided thing. We don't know why or truly if Nidhogg attacked the early Ishgardians. Part of me cant help but suspect we might be dealing with grudges that might tie back all the way to the Allag.