Garfield is the name of a daily comic strip that has run for upwards of 30 years. The eponymous Garfield is a cat. He's fat. He's orange. He hates Mondays as much as he loves sleeping. You can find his website here.
Like Calvin and Hobbes, it is somewhat bizarre to find fanfiction for Garfield. Comic strips consist of fat, lazy Garfield commenting on his goofy owner, kicking his housemate dog Odie off the counter, and eating large amounts of lasagna. There was a cartoon show in the vein of the comic strip, and it kept the tone fairly consistent—and also some live action/CG movies of questionable quality that may have boosted its popularity.
Why any Suvian would ever go to this continuum is unknown. But it happens. It's just more proof that Mary Sues cannot be fathomed. (Note: Arlene was prety much a Sue from the start. So no sneaky attacking the canon character...)