At some point, two Riverclan warriors decided to have kits. They'd been dancing around the idea for what felt like a lifetime, and when they finally scraped together the courage to give it a shot, they were quickly blessed with exactly what they'd wanted - kts, or least the promise of some. 
One kit, a tom with tabby fur and big eyes, was the fruit of their efforts, and you wouldn't find two parents more proud of their son. As he stumbled from a ball of fluff to an adventurous young cat, they watched him grow and explore, a whole life ahead of him.
Shortly before his apprentice ceremony, he developed a cough that quickly turned and fatal, and he died at the age of six moons.
His parents, as you would imagine, were crushed at the loss of their only son, and the idea of having more kits didn't cross their minds for many more moons. When it did, it was at the tom's suggestion - they hadn't really gotten the chance to be parents, and the odds of them losing another kit were slim. His suggestions soon turned to desperation, and the she cat found a similar wish to fill the hole in her life. She became pregnant, but there wasn't the same air around her this time.
Two kits, a tom and a she cat. The tom, first born but the smaller of the two, had grey tabby fur like his mother; the she cat, like her brother before her, had the brown tabby coat of her father. After moments of deliberation, they were named Ashkit and Ivykit.