A superhero may fight crazed villains, towering monstrosities and mutated supergeniuses, but along the way the hardest battles are usually with himself and with some of the big questions. Golden Age and Silver Age comics might take it for granted that a man could put on a costume, remain entirely stable and sane and be accepted by the military and law enforcement as an axillary member of their team.

That assumption still pervades many titles, but rarely with the same glib self-assurance as before. The X-Men represented the ultimate alienated superheroes, mutated and despised and persecuted, by the very people they were trying to help. But increasingly many superheroes fall in the same category. After all beneath his bright cape and All American color scheme, what is Superman really but an alien from another planet? What is Daredevil, but a human with a mutant power. Or Spider Man for that matter? What is Batman but a borderline schizophrenic in freakish costume?

A man or a woman, in costume, can no longer expect to have a comfortable relationship with the rest of society.Nor can we expect such a person to be too well grounded sometimes.

Cut off in this way a superhero then has to make his own moral decisions and set his own rules? What is justice? Can you kill a villain, or only incapacitate him and deliver him to Arkham Asylum? Uncomfortable questions for unstable superheroes begin arising.

How many times has Batman hunted down and imprisoned the Joker, only to have the Joker escape again and resume killing people. How many lives would Batman have saved, had he killed the Joker, instead of repeatedly capturing him? And doesn't the same go for so many of Gotham's other villains? The Joker is certainly the worst with a body count in the thousands if not the hundreds of thousands by now, but he's certainly not alone.

Guided by an ethos that says "Spare your enemy because you are better than him" and "extend your hand to the lunatic mad scientist as he's falling off a cliff after the explosion of his laboratory", are the superheroes really living by a sane moral code?

But what is the alternative? Superheroes step out on a limb by becoming freelance police officers. Most do not also choose to become judge, jury and executioner as well.

Primarily superheroes fill gaps in abilities and powers by conventional law enforcement forces and the military. Superheroes may fight organized crime that is too ruthless and deeply embedded for law enforcement to deal with. They may and do fight villains who have superhuman abilities, that are beyond the conventional abilities of police forces to combat. They may fight extrasolar entities who come from outside our solar system to wreak havoc on earth, which is beyond the ability of ordinary military forces to combat.

Stepping beyond such auxilary roles into confronting and destroying villains, puts superheroes outside of society altogether, no longer merely aiding, but either denying outright the laws and values of society or claiming the right to supersede them.

The integration of superheroes into a society remains a point of contention, reflected in numerous storylines including Marvel's recent Civil War storyline. Legislation is often passed that restricts or limits superheroes and what they can do, such as the Keene Act in Watchmen. Superheroes are already very strange and different, a superhero who ruthlessly kills crosses the line into outright terrifying.

Superman is an alien with virtually unstoppable powers. A Superman who dispensed freelance justice, would no longer be a partner, but a tyrant. There is only so far outside society's rules a superhero can step and still be any different than the villains he or she fights.

It is no surprise that those heroes who step over that line and become murderous vigilantes, most prominently, are all too human. Consider Rorschach in Watchmen or Marvel's Punisher. Frank Castle is a former police officer, with no superpowers but his guns and grenades. ("Who needs superpowers when you have a hand grenade?" asks a character as a superhero association in an issue of "The Tick.")

While Frank Castle lives and fights in a world filled with superheroes, men and women who in theory should be capable of squashing like a bug, The Punisher holds his own.Garth Ennis' "The Punisher Kills the Marvel Universe" even famously shows him hunting down and killing all the superheroes of the Marvel Universe including Spider Man, Wolverine and Daredevil, after a superhero battle results in the death of his wife. Garth Ennis has always rather famously overestimated The Punisher's abilities and has traditionally been comfortable with rough men in guns, rather than superheroes, something he demonstrated equally well in his run on Hitman.

Loosely based on the Mack Bolan novels, Frank Castle is essentially a men's adventure cliche, in his own costume and focuses on the violence minus the sex. A killing machine with no principle besides killing the bad guys. As he finds them. Frank Castle's moral code is law and order, absent the trickier questions. He is the logical end result of the vigilante hero. Morality must come from the inside or the outside. As the comic book universe has grown darker and its heroes more alienated, their morality is no longer the confident projection of social norms, but must come from within.