But other than being a cute animal that provides a layer of eccentricity to Trek’s newest daring space pilot, is Grudge really just a cat? Book speaks of Grudge in ways that makes the cat seem perhaps more sentient than we think. Perhaps we’ve all been conditioned by the cat in Captain Marvel — Goose — which turned out to be an alien Flerken. Or maybe we’ve been conditioned by that episode of Star Trek: The Original Series, in which the black cat Spock was “strangely drawn to,” appeared to be a shape-shifting woman at one point in the episode.
Although previous Star Trek pets generally aren’t revealed to be aliens — they are sometimes. In the TNG episode “Aquiel,” Geordi takes care of an abandoned dog named Maura, who turns out to be a blob monster called a coalescent organism. Janeway and Kirk’s aforementioned dogs weren’t ever really seen in the fur, but rather, the animals we saw on screen were either telepathic nexus creations or tricks created by Q. (This is kind of like the idea that people rarely ride “real” horses in Star Trek. Usually just holographic ones or “dream” horses.)
Data’s cat was a real cat. But then again, we’re not totally sure. Spot changed appearance radically throughout The Next Generation and even went from being male to female and back again. In Picard, an orange tabby named “Spot II” is revealed to be totally synthetic by Data’s human brother, Atlan Soong. In a non-canon comic book short story from the IDW comic Star Trek: Waypoint, it was revealed that Porthos was actually a time-traveling dog, and that via time-travel, he actually saved Archer’s life when Archer was a little kid.
The point is, outside of Picard’s fish in TNG (Livingston) there’s generally some kind of sci-fi plot twist hanging around pets in Trek. Think about the most famous pets in all of the franchise: Tribbles. They look like furry cute balls, but of course, there’s some infamous “trouble” with them. This doesn’t mean it’s a foregone conclusion that Grudge is really a shapeshifter, or has telepathic powers, or is a time traveler just like Burnham, but then again, you never know.