[How about this: three states for the power,] Bella says. [By default, you don't need to breathe, but you will anyway if you're not paying attention, so you don't freak out observers. Change it on purpose, and you can inhale whatever you want, suffer the usual effects uninhibited, fun stuff. Fall unconscious, and you don't need to breathe anymore and your body will not automatically try to do it in case that would make things worse, but will expel whatever's in your lungs at the time.]