@Eclipse01 It's possible the genetic medicine he brought back is the catalyst for doomsday. If he were to gives it out, people are bound to steal it for research. They then can cause some type of mutation accident which would start all of this doomsday scenario. It's the chicken and egg dilemma. Which came first the chicken or the egg. Which is the cause and which is the effect?
@acetate If the origin of the drug is our MC, then it's a time paradox. It means no one actually invented the drug, it just exists.
On the other hand, if there is a creator, then the fact that he invented it will rewritten so that MC created it, but then there's no creator anymore and the drug came out of nowhere. TIME PARADOX