10 to the 16th to 1 (Unabridged‪)‬

Here's a time travel tale that takes place during the Cuban Missile Crisis. 12 year-old Ray stumbles upon an android from the future that has been sent back to 1962 to change the course of our history. What he asks Ray to help him do will shock you in this gripping story of impossible choices. This story won the Hugo for Best Novelette in 2000.
Author James Patrick Kelly is a two-time winner of the Hugo Award and a 2007 Nebula Award winner. His stories appear frequently in Asimov's Science Fiction, and he writes the magazine's "On the Net" column. Publishers Weekly has called him "a meticulous craftsman in the demanding short-story form".