In the comics, the Punisher isn't simply heartless. His actions are a result of his traumatic past and a determination to fight crime by any means necessary. It's a mix of passion and a warped sense of morality.
I don't think there was a character named Karen in Punisher comics. Usually, the main characters and well-known ones are pretty distinct, and I haven't come across a Karen in this series.
Well, 'Punisher: War Zone' is a great one. It has a lot of action and showcases the Punisher's determination and no-nonsense approach. Also, the 'Welcome Back, Frank' storyline is highly regarded for its depth and complexity.
Well, first, you might want to look for a recommended reading order online. After that, get yourself in a quiet and comfortable place, and start flipping through the pages, taking in the action and plot. Also, make sure you have good lighting to fully appreciate the details.