Severus Snape

So, while reading Plato's Republic, on page 45, I read Glaucon's account of the perfectly "just" man - and got that eureka! moment. This description came when Glaucon was saying that one needed to have a perfectly just man and a perfectly unjust man, and judge them against each other to determine which was indeed happier. And his description of the perfectly just man was strikingly similar to many movies and TV shows that I have seen. "Our just man must have the worst of reputations for wrongdoing even though he has done no wrong". My first two thoughts were Severus Snape from Harry Potter and House, played by Hugh Laurie in the TV series, House.
Both of these characters are ones whom you only learn about their amazing sense of ethics in very short bursts or at the very end of their life. Their entire "justness" is concealed in their "UNjustness" - and Glaucon argues that the truly just man is always SEEN to be unjust, while the truly unjust man is seen to be just.
The fact that this idea is still prevalent in modern society is a testament to its accuracy. I personally always thought that Snape was just the most self-serving coward who lacked any ethics at all. He is then, at the end of the books, shown to be the one who, in fact, has some of the highest ethical standards.
House plays this mean doctor who seems to be all in it for himself. He shows no empathy for anyone else and actually delights in their misery. However, every now and then there are slight glimmers of him in which you realize, wow, he is actually super-empathetic and CARES so much - but he has to hide it under this shell of aloofness and cruelty.
I just wonder if there is any credence to this theory. Are the people who actually seem to not care at all some remarkable human beings, while some other angelesque people are, in fact, quite malicious? It seems to be the case with most politicians at least. Or is there a more murky, not as clear-cut definition of the "just" and "unjust" person?