Yeah I've known a few 'brilliant' coders over the years -- and they knew it too, not arrogant or anything but completely self assured -- but by far the scariest coders as a group were Russians. These guys had all worked on some crazy military project back home -- one fellow had helped program the guidance systems of the Russian cruise missile -- and they had a way of looking at and solving programming problems that was like watching a black box perform magic. They were to a man cheerless bastards and very insular but made a point of being pleasant to work with and always produced top shelf results.