The story goes that while Ernest Hemingway was in Cuba, he stopped in to Floridita's to use the restroom and decided to try their signature Daiquiri. After tasting it, he said, "That's good but I prefer it without sugar and double rum." The Hemingway Daiquiri, or Papa Doble, was born. Supposedly the maraschino liqueur and grapefruit juice were added later, and it became known as the Hemingway Special.
Well-balanced at these proportions, very similar to a classic Daiquiri but the Maraschino and grapefruit add some nuttiness and additional citrus flavors.