The Cheshire Cat.
The Black Stallion.
What do all these have in common? 1.) They're all secondary characters in a novel, and 2.) they're all animals.
Furry, feathered, finned, or scaly creatures have been a popular device in many, many stories. From dogs and cats to wolves and horses, from dragons and snakes to bears, birds, even dolphins--animal cohorts have been loyal companions and guides for the hero since the dawn of story.
Animal as secondary characters play many roles in fiction. Let's examine a few of the popular examples:
The Loyal Companion (Most dogs, horses, and wolves): The loyal companion loves the hero completely and without reservation. He isn't there for his own gain or because he's being forced; he's there because he wouldn't be anywhere else. The unwavering loyalty of dogs and wolves make them popular loyal companions, and horses often fall into this category, too. They ask for nothing, and defend their person whenever they can, even at the cost of their own life.
The Mysterious One (Almost all cats): These animal cohorts are more aloof and independent then the Loyal Companion, keeping their own council and company. They are crafty and intelligent, and their motives are usually murky and unclear. Cats are almost always portrayed as mysterious creatures who think they are smarter then the hero, and are usually right.
The Bonded (Lyra's Daemon, the dragons of Pern, horses, wolves, cats): These creatures have some supernatural connection with their "chosen someone," allowing them to sense their emotions, hear their thoughts, share magic, and more. The bond is usually extremely powerful, overshadowing the pair's entire life, and if one partner dies the other usually pines away or perishes as well.
The Trickster (Small dogs, monkeys, foxes, rodents, birds, ferrets, ect.): These animal cohorts are usually too small to provide anything but comic relief and handy ways to escape seemingly impossible situations. Locked up in a jail cell? Send your feisty terrier to grab the key. Need to swipe something unseen? Your monkey can do that easily, or at least provide a useful distraction. Careful though, because small cute trickster cohorts often meet tragic ends, to show off their extreme loyalty and to pull at reader heartstrings. (Hedwig, anyone?)
The Protector (Dragons, bears, wolves, large cats): Large, powerful, noble creatures who are there to guard and protect the hero fall into this category. Sometimes, they can overlap into the Bonded category, as well, but all have the ability to fight alongside the hero, and often save him from untimely death on more then one occasion. Though, like the Trickster, sometimes they lose their own life to ensure the hero escapes safely, though they are always noble and self-sacrificing about it.
The Familiar (Cats, small furry creatures, tiny dragons): Similar to the Bonded, Familiars have a chosen someone, and might even be able to hear their thoughts and feel their emotions, but they are primarily there to assist the hero in magic. Sometimes teachers, sometimes assistants, Familiars are usually very knowledgeable in their craft, and when things blow up or go wrong, it is almost always the human's fault.
That's all I can think of right now. Who are some of you favorite animal companions in books and movies? And if you could have an animal cohort, what would you choose?