Rick from Rick and Morty has a specific rule about killing that suggests the show's first real villain had a bigger advantage over him than fans realize. When facing a group of powerful individuals with an axe to grind with him and Morty, the duo defeats them but Rick admits that he cannot bring himself to kill the galactic crime lord Party Dog. His reason why sheds a new light on Rick's plans against Morty’s dog Snuffles who, thanks to Rick, became hyper-intelligent and nearly assembled a robo-canine army to take over the world.
In Rick and Morty #41 by Kyle Starks and Marc Ellerby, Party Dog has finally learned the location of the man who killed some of his lieutenants during a prison break gone wrong and sends the word out to like-minded entities also seeking payback. The Rick Revenge Squad successfully surprises Rick and Morty, threatening the lives of not only the titular duo but of the entire Smith family. When the Squad members are outsmarted, beaten or even killed by their targets, Party Dog and his posse of armed, sunglasses-wearing sentient arthropods arrive to finish the job. Despite their numbers and firepower, they are no match for Rick and Morty and the last animal standing is the vengeful and annoyed Party Dog.
In Rick and Morty #42 by Starks and Ellerby, surrounded by Hawaiian-shirt wearing animal corpses, Rick admits that he cannot kill Party Dog, or any dog for that matter. Despite being reminded that he isn’t a dog but a creature that appears like one, Rick tries to pass it onto someone else present admitting, “I have a minimal amount of hang-ups, but I can’t kill a dog. Y-You’d be a monster to do something like that.” When not even Jerry will agree to kill Party Dog, Rick teleports away, claiming that he’ll be back soon with a solution.
Rick and Morty has always been known for not its homages and references, but also for its self-awareness. Rick's genius and ego combined can be an unstoppable force that has toppled intergalactic governments or powerful enemies alike with little concern about the lives lost as a result. Despite Morty pointing out that Party Dog isn't actually a real dog but merely an entity that appears like one, Rick draws this line in the sand and even acknowledges that it doesn't make sense but still stands by it. It also sheds a different light on the first real villain the duo faced, Morty's dog Snuffles from the Season 1 episode "Lawnmower Dog," who sought to takeover the world and enslave humanity. Rick's stance means Snuffles and his soldiers had an advantage that other enemies of Rick did not, which explains Rick's strange and convoluted plan to influence the animal via dreams. He would rather Snuffles take his army and other dogs to start their own colony in another dimension instead of killing them, proving underneath all that booze and insults there may be a few small shreds of decency left within the grumpy old man.
When Rick returns, he reveals that while he and the Smith family have reservations about killing or harming a dog, another dog does not as Snuffles returns briefly to show Party Dog the error of his ways. Although the fate of the crime lord is left ambiguous, this random, surprising establishment of boundaries within Rick's personal and professional life is both amusing and kind of sweet. It appears Snuffles holds no grudges against his former masters, and one can hope he doesn't change his mind as Rick and Morty would have to once again come up with a non-lethal solution to get out of that situation.