Why do pets and animal companions in fiction feel so immediate, so universally legible, and so devastating when a story takes them away?

We pull threads from everywhere, comic book pets like Krypto, the daemon companions of His Dark Materials, and the long mythic history of loyal animals that reveal a hero’s character. From Odysseus and Argus to the Mahabharata’s stray dog test, we track what separates a true companion from a symbol or a beast of burden: mutual attachment, choice, and the kind of love that costs something.