Many passionate tales are born out of sibling rivalry. Cain and Abel. Romulus and Remus. Sam & Max: Freelance Police.
This particular tale starts way back in the disco era, when budding artist Dave Purcell invented a comic about a dog and rabbit team of detectives, Sam and Max. Dave would often leave unfinished comics lying around the house. To torture him in the way that only siblings can, older brother Steve would finish the comics as parodies of the stories Dave was trying to tell, with Sam & Max messing up each other's names, shooting at each other, and making fun of how they had been drawn.