Time travel
That desire of "undo" is so strong amongst so many of us that probably each one of us kinda long for time travel to change the decisions that we think have impacted the outcome we face today. Time travel and paradox are my favorite themes in comics, movies or any fictional readings/writings that I attempt. Watched Flashpoint paradox yet again and loved it thoroughly. Here's the list of movies I have loved so far on these themes: Predestination, Flashpoint Paradox, The Butterfly Effect. Can watch each one for umpteen times.