Oooh good question. Kellie is technically part of a sub-race named aurigens, which were developed during the war between the kanines and felynes. They have special powers they pass down genetically called aurability. Every aurigen comes pre-installed with various defensive abilities engineered to make them really sturdy: they can resist almost any physical trauma, can withstand heat and cold and pressure and vacuum, and even some supernatural stuff like telepathy and telekinesis. But some of their main abilities are offensive, they can give themselves super speed, they can emit pulses of electricity that will fry anything electronic nearby, and they can turn off their empathy and become killing machines (which was necessary for the normally kindhearted kanines. It was war.).
These powers are normally voluntary. Most aurigens have no use for them anymore. Kellie’s powers are a bit more sensitive, since she’s an unusually powerful aurigen. Its probably safe to say theres never been an aurigen with such strong power before. So certain foods set off kellie’s powers. It isnt just candy, it’s a wide variety of sugars. It isnt just sour candy, its a wide variety of acids. Chocolate is a more specific one, the compound in it is specifically what triggers her. It’s kind of like a messed up immune response.