Both Dexter and House are in the business of saving lives, in one way or another. And both are individuals who are somewhat nasty. And both operate by breaking the rules on a regular basis. Does the fact that they save lives excuse Dexter’s and House’s faults?
Before we consider the question properly we must clearly understand what their faults are. It is not reasonable to blame them for doing something that, by itself, is bad in order to bring about a good outcome. Of course some would blame them for doing just that, but they would be wrong to do so. Some would see justifying the means by the end as ethically unsound, and on those grounds would not excuse what they do because of the good that it brings about. Such objections are often justified by appealing to the many times when a good result has been used to justify evil actions, and the fact that we would prefer to ethically condemn people who act in that way. But the examples brought up in such an argument almost always involve an end which is thought to be good by the person acting, and portrayed as good to others, but is actually evil, or involve situations in which the evil actions being taken won’t actually yield the desired good end. So to meet this objection half way we can further stipulate that the end only justifies the means when the means are known (in a strong sense) by the people acting to bring about that end and that they know that end to be good. Even given that restriction both Dexter and House are still justified in acting as they do, since they both know that what they do is likely to work, and they know that the end result is more people alive.
What is questionable is the fact that they both break justified rules to act as they do. Obviously not all rules need to be obeyed all the time, but there are good rules, rules that make us all better off when we follow them. And the legal (specifically the ones prohibiting vigilantism) and medical rules involved in both cases are such rules. Breaking such rules can itself be considered a bad outcome. If people break them then the rules have less force, and are thus less effective, and so we all end up less well off. And there is also the problem that they are both motivated primarily by selfish reasons. And we can’t praise selfishness or we run the risk of encouraging more people to be selfish. Thus we are moved to condemn them because they exemplify patterns of behavior that we wouldn’t want to see adopted by other people.
But, on the other hand, it is pretty clear that their fictional worlds are better off with Dexter and House in them than they would be without them. And partly this is because neither character is the kind of person that encourages others to act like them. Dexter is secretive and House is abrasive. So their existence doesn’t encourage other people to be like them; to break the rules like they do or to be as selfish as they are. And thus the problems mentioned above are to some extent negated; if your breaking the rules doesn’t make other people want to break the rules then you have done nothing wrong (assuming the results of the action that broke the rules were good).
So Dexter and House could probably justifiably consider themselves to be good people. But we are in a trickier situation. If we describe them as good people then we are encouraging other people to be like them, to break the rules and to be selfish. And so it seems like we are forced to condemn them, despite the fact that they make the world a better place. But actually there is a way out. We can condemn people like Dexter and like House while consistently holding that Dexter and House themselves are good people. This is much like claiming that theft is wrong while admitting that there are occasional examples of theft that are acceptable. Similarly then Dexter and House are the exceptions, the two selfish rule-breakers who we tolerate while condemning the rest.