In The Beast at the Gate, Nephredom is a rather complex character whose life is filled with both triumph and tragedy. He is an ambitious man, but he is motivated more by revenge than power. He is also slowly going insane. But without giving too much away, I would say that his madness has certain external causes, and his own arrogance has caused him to ignore the obvious signs. Nephredom is arguably the lead villain in the story, but is by no means the only one.
He is, in my opinion, the most redeemable villain--if such a thing is possible. There is a certain rough nobility in Nephredom that drives him, and in that sense, gives him a degree of honor. Of course, the heroes in the story would vehemently disagree with that assessment.
Nevertheless, what if blind vengeance and hate had not been allowed to take root in his heart? Would he had used his powers for good? Maybe...maybe not. Who knows what kind of life Nephredom would have led if the circumstances had turned out a little differently. Well, technically I would know, but that's a tale for a different time.