The Flash
One of many lessons that I got after watching The Flash is, although you are able to travel in time, there are things that you cannot simply change. I actually wept a bit watching these scenes. The thing about being The Flash, Everyone in the Central City thinks they are fortunate enough to have someone to rely on, when something bad happens. But he himself is never happy. He may seem happy on the outside but apparently, he is hopelessly sad inside, especially when those tragic memories strike.