>>94572544Peppermint Patty was originally conceived as the main character of a separate strip that took place in the same universe as Peanuts, but Shultz decided he didn't want to be writing to strips at once, so just made her a common side character in Peanuts. The fact that she was supposed to be a protagonist really shows. She's deeply flawed, but also incredibly sympathetic, easily on par with Chuck himself, if not moresoe, she definitely has bigger problems than Chuck, if not more frequent ones, and she's happy a lot of the time. She's much more of an emotional roller coaster than Charlie Brown, pleasant highs and devastating lows, where as Chuck just sort of drifts from general woe to light contentment.
In some ways I think Peppermint Patty being a part of peanuts was a mistake, since in her interactions with Chuck, the audience is generally supposed to take her side. Chuck is making her life worse, too self-absorbed to have any sympathy for anyone else. In a spin-off this could really be cool, seeing Charlie Brown from someone else's perspective, and really seeing him in a less flattering light. But in Peanuts itself, a big part of it is the reader sympathizing with Charlie Brown, being in his shoes, feeling bad for how unfair life is, and that's really undermined when we see him crushing Peppermint Patty like he does.