Should you want to add an animal to your story, here’s the First Rule of Thumb: the more important the fictional animal is to your story/plot/series, the more you need to know about the actual one. That being said, here are some snippets that floated through my brain while thinking about fictional animals
Second Rule of Thumb: if you want your readers to identify with the animal, consider a dog or cat. In most Western countries, the two most popular pets are dogs and cats. There are approximately 75.5 million pet dogs and 93.6 million pet cats in the United States—compared to 5.3 million house rabbits. On the other hand, more households own dogs than cats—45.6 million households vs. 38.2 million households, respectively. Among college students, 60% identified themselves as dog lovers compared to 11% cat lovers (everyone else being both or neither). (And just a fun fact: in 2013, pets outnumbered children four to one in the U.S.)
Sticking to dogs and cats for a bit: dog owners report seeking companionship, while cat owners sought affection.
If you do go with a dog or a cat, consider how the profile of the typical owner matches your character. Overall, dog lovers are more energetic and outgoing, and are more likely to follow rules closely. Cat lovers are more introverted, open-minded, sensitive, non-conformist, and intelligent. As most people know, dogs and cats of various species have identifiable personalities and behaviors, so consider how compatible or incompatible your character and pet need to be to support your storyline. Which is your dog?
Third Rule of Thumb: the more unusual the animal you choose, the more you might have to work for reader affection but the easier it might be to grab reader attention. Consider the red-footed tortoise.
Only 4.7 million U.S. households own reptiles, and many of those are lizards, snakes, etc. Chances are a red-footed tortoise would be pretty unfamiliar. Few readers would know that they can grow to more than 18 inches, and live more than 30 years. Some readers would be interested to learn that they are omnivorous, rest 50% of the time, and prefer temperatures around 86 F, not below 68 F or over 95 F. What sort of character would choose such an animal companion? What sort of household might own four dogs, six cats, one parrot, and a tortoise?
BIG TAKE-AWAY FOR WRITERS
Think carefully before you throw one or more animals into your story. Consider the role of the animal(s), and the fit between your character and the fictional animal(s). And then have fun with it!
P.S. FYI, January 14th is Dress Up Your Pet Day. Work that tidbit into your story!