Who is Marley from Marley and Me and what is their importance?

Marley is a golden Labrador retriever. He is rambunctious, strong-willed, a trouble-maker, property destroyer, shoulder to cry on and teacher.

John and Jenny Grogan decide to get a dog as training for being parents. Jenny picks out Marley after he runs at her while his brothers and sisters shrink back from John's scare tactics. Marley's mother is calm-tempered while the only glimpse the couple gets of his father is a muddy blur screaming out of the woods and whipping around the house. John is a little concerned that Marley will take after his crazed father, but they purchase the puppy anyway. Marley is named after Bob Marley, whose music welcomed John and Jenny when they moved to South Florida from the Midwest.