Despise her devilish personality, Kepler-70 is actually very smart, which is a reason why some people call her a "Mad Scientist". She murdered Kepler-70b because when she was a yellow dwarf, she hated both of her daughters for trying to make silly jokes of her. But probably at least 200 million years ago, she finally got into her red giant stage and tried to kill both of her planets. Her plan worked with the closest of the 2, Kepler-70b, but NOT Kepler-70c.