Lydia / Parrish
My other theory is Reactive Adaptation. Users can either instantly develop powers or abilities to deal with threats or their bodies dynamically learn from experience. After a certain situation the user's skin may become tougher, they may display increased IQ after a difficult test or fortified emotions after a personal argument. User may be able to read different languages after moments of looking them up or be able to withstand a constant bombardment of radiation. Some users may develop Enhanced Speed after being shot, or grow Dermal Armor, and may have the opposite power of their opponent.
What? No way. Not death, specifically, but we're not done with this. I can handle anything.