Calvin and Hobbes
' Bill Watterson and Bloom County
's Berkeley Breathed have a decades-long friendly feud. Where Watterson is principled and reclusive, Breathed doesn't mind merchandising his creations, and can't say no to a good convention appearance.
In a 2010 Comic-Con panel, Breathed showed off some original Watterson artwork that had never before seen the light of day - because they were private missives roasting Breathed into oblivion.
This is what happens when 90's-era comic artists stop being polite... and start getting real