Some people prefer dogs, some prefer cats.
Cats are aloof. The friendly cat exists but one should always be suspicious of them because they definitely want something from you. But cats can warm up to you over time. The cat owner feeds it and shelters it, invests time and energy into the cat, spends every evening begging the cat for attention. Eventually the cat may conclude that you’re a worthy human after all, allow you to pet it without scratching your hand off, and maybe even curl up in your lap next to the fire. The cat owner, by now terminally stricken with Stockholm syndrome, will convince herself that it was all worth it and that cats are the best pets ever.
The dog starts friendly. Their loyalty is easily bought with bones and games of fetch. Where cats will barely acknowledge your presence dogs will go ballistic just knowing you’re coming home, tackle you as soon as you set a foot through the door, and drown you in dog spittle. Dogs are known as man’s best friend for a reason, and they are eager to demonstrate; a dog on a walk will zealously lash out at other dogs, motor vehicles, and baby prams just to prove that they are definitely on your team. The domestic canine, sans the ones kept in the yard to murder postmen, have been bred over countless generations specifically to be liked and it’s very easy to do so.
In a story with a large cast there will also be cats and dogs. The most interesting characters are often cats. They don’t start out particularly likeable (cute though they may be), but we get to know them, and they grow on us. That is, they go through a character arc. King Gilgamesh, for example, would be a cat. He starts out as a douche but he gets character development over the course of the narrative. This is how a proper story should go. In that case, though, what are dogs for?
In stories, dogs are there to suffer.
Dogs start off good and wholesome and likeable. They don’t really have many places to go as a character other than down. And so they do. Ushiwakamaru was very much a dog (some kind of bloodhound, perhaps), very endearing to our protagonist, obvious in appeal, and doesn’t wear human clothes. Likeable characters are, unfortunately, great fuel for drama. Note how many stories, especially those vying for some sort of children’s literature award, in which the dog has to die.
It’s a technique Nasu loves to use and abuse, turning once heroes into the villains. The most effective villains are sympathetic ones and they’re easily sympathetic if they used to be good guys. We feel sorry for them. Watch as Nasu does it three times in a row in this single episode. We’re supposed to feel sorry for Ushiwakamaru. And Kingu. And, of course, Siduri, so much so that she gets her own ED.
Isn’t this a bit much? You can’t expect me to be a decent human being. I don’t have that much empathy to go around.
ED3: 「Tell me」 by milet