You may save the life of one person, and one person only, from any point in history. This person must have died by a means other than natural causes/old age. As part of the deal, the person is guaranteed to live until they die of old age.
For the sake of argument, no matter what changes to history your actions make, you and your loved ones will still be born.
Some ideas to get you started: would you save Archduke Franz Ferdinand and hope it would stave off one or both World Wars? A great scientist like Archimedes or Evariste Galois, and hope their genius would have brought scientific advancements to the world that much sooner? A great artist like Mozart or Van Gogh? A political or social leader like Julius Caesar, Abraham Lincoln, Vladimir Lenin, Martin Luther King Jr, John F Kennedy, Salvador Allende or Yitzhak Rabin? Jesus Christ? Someone in the right place at the right time- say, the pilot of one of the flights that hit the World Trade Center, or one of Hitler’s attempted assassins?
My choice would be Alexander the Great. Alexander died young from illness, after conquering an empire that stretched into Africa and Asia. Without him, the empire quickly disintegrated. The Romans would later repeat Alexander’s efforts in Egypt, but otherwise the borders of the world would be set for at least 1500 years: Europe, Africa and Asia all separate, with that failure to interact retarding humanity’s social and technological development while building racial and cultural barriers which persist to this day. A healthy Alexander, with decades to increase and consolidate his conquests, may have seen the bulk of Africa and Eurasia if not permanently unified (no empire lasts forever) then at least familiar with and communicating with each other instead of treating the unknown as inferiors, heretics or devils.
Ladies and gentlemen, who will YOU save?
