I once saw a documentary about futuristic technology and it described a very disturbing usage of nanotechnology. Even though nanites can be used to cure cancer, heal injuries, and improve human physical conditioning, they can also be used for more sinister uses. Instead of healing, nanites could theoretically be used as a technologically advanced torture device. Once injected into a subject, the nanites would tear the subject apart atom by atom. This way, the nanites would operate like a flesh eating disease that eats them from the inside out. I am thinking of drawing inspiration from this concept in order to come up with the origin story the first supervillain in my new superhero series. It will be horrid, but the end result will be terrifying.