I'm half asleep, but my dog, Rascal, is wide awake. She's 2 1/2 and still thinks she's a puppy. Not only that, despite my taking her to obedience classes (where she behaves like a model student), she shows little respect for me at home. She grabs my slippers, sometimes grabs my hat or gloves right from my hands, you get the picture. If she weren't so cute, I'd hate her.
So, what does this have to do with writing?
Pets make great fodder for writing. They can add an extra dimension to your characters. If your main character seems a bit rough around the edges, but you want to show that your character is likeable, consider letting that person own a dog, climb up a tree to rescue a cat, or work at an animal shelter.
This can also work for the villain in your story. To show a human characteristic and make the villain more well rounded, you can make him or her soft for his German Shepherd, or even a gold fish. Maybe the pet is the only one the villain can relate to.
You can carry this a step further by making a pet the major character of your book, such as John Grogan did in Marley and Me.
Rascal, one of these days you may be a star.