It has been a long time since I have read comics, but he was basically an anti-hero. He did a lot of stuff that was straight just bad, torturing people for information, and just a lot of over the top use of force. He doesn’t see himself as a hero, and he regrets getting into the life hie is in, because it’s just a lot of killing, and not always killing “bad guys”, plus it leads to people he cares about always being collateral damage.

He was a marine, whose exact story shifted, but was basically some sort of black ops, or some sort of special operations, sometimes he’s a seal. But his family coincidentally witness a mob hit and they get killed over it. Frank returns and goes into a period of depression and alcoholism, then decides to kill the mafia organization that did it. This just lead him into a never ending path of revenge, turning to people seeking revenge on him, turning to him killing them, and so on.