Originally created as an antagonist to Spider-Man, Frank Castle, a.k.a. "The Punisher," has remained fairly consistent throughout his comic story lines as well as his film and television adaptations. There's no drastic character change. The Punisher finds evil. He kills evil.
Castle was a Marine Corps captain and scout sniper who witnessed the death of his family. He then vowed to eliminate crime using the best super power the Corps could give him — his deadly accuracy as a rifleman.
Fans immediately drew to his methodology, professionalism, and undying will to bring peace through warfare. And he quickly became a popular icon within the military community.
Everyone loves and knows him for his service in the Marine Corps, but what would it have actually been like to serve under Capt. Castle?
You would train. Hard.
When your commanding officer is sniper, airborne, underwater demolitions, and SEAL qualified, you and the rest of your Force Recon team need to get on his level.
The only time you'd get off would be for religious purposes (since he was a devout Catholic, even almost becoming a priest until he enlisted in the Marines.)
In the 43 years of Punisher comics, he's been shown to be a master of damn near every weapon he has ever gotten his hands on. Hell, he even uses other heroes' gear more effectively than they can.
The skull logo would become your new unit insignia.
Everyone would be as decked out as SEAL Team 3 in Capt. Castle's logo.
Judging by Garth Ennis' take on The Punisher's time in Vietnam in the series Born, he was pretty loose when it came to uniforms.
Then again, either you'd be in his Force Recon team or he'd carry his "battle beard" standard over to your unit's wear and appearance standards.
The rules of engagement would ... change.
Capt. Castle has a strict code on justice.
There wouldn't be any turning a blind eye to one local warlord because they dropped the dime on a rival warlord who was also a terrorist. They're both guilty in Capt. Castle's eyes.
If you're a sh*tbag Marine, he'd f*cking kill you.
Following the previously mentioned "Born" comic, we saw what Capt. Castle was like as a commanding officer.
In issue #2, after all of the chaos of battle, Castle finds one of his privates sexually assaulting a wounded female enemy soldier. He puts her out of her misery. While the private was cleaning himself off in a nearby river, Castle drowns him in the water saying that "we're only here to kill the enemy."
If you not only broke the law but also basic human rights, you're no different than the pieces of sh*t he kills on a daily basis.
If you're a good Marine, he would take care of you.
The only bright side (outside of a sick SOCOM battle beard, of course) would be that Capt. Castle takes care of his own.
He protects his own. He saves his fellow heroes and troops countless times. If he ever fails, well, the ones who killed you will be punished.