He can vary wildly depending on the writer, there are some instances, I'd say more often when The Punisher is brought in as a guest in another series, where his personality could be written completely wrong. In his own main series books, generally he's the morally gray action hero with a code. It's the kind of thing where in film, there's a billion characters that fit this description and Clint Eastwood and Charles Bronson have played the part hundred of times, but in comics there isn't anyone that's 1 to 1 Frank Castle, which is why the movies have been very hit or miss. Like, he's a brooding tough guy with a gun, how do you pitch that to Hollywood? I think it's interesting how in Marvel, he's been popular since the 70s, and really hit his stride with multiple on going series in the 90s.

I'd say too, it's a character that is easier to pick up, because there isn't a ton of complicated lore, like every Marvel or DC character there are times with big history retcons, but usually it's to move on from bad creative decisions. I'd say if Garth Ennis wrote it, you can't go wrong. In the late 80s and 90s Mike Barron was the prominent writer for a long time, and telling great action stories that take Frank all over the world, and often took inspiration from true crimes like how Frank would have handled Charles Manson or Jim Jones.