Avengers: Age of Ultron opened my eyes at the end of the movie when one of it newest characters died.
Quicksilver sadly, while saving Hawkeye was shot by Ultron with his dying words being " You didn't see that coming."
While I was sad I also was impressed with director Joss Whedon and agreed with him killing off a character. Because it shows that heroes can die and that makes the stakes higher for our heroes in the MCU.
Although many heroes have died and came back to life, such as heroes like Nick Fury, Bucky Barnes, and Iron Man. This makes us feel like nothing bad will happen to our heroes and makes it less saddening and exciting when a hero dies.
I hope that Quicksilver stays dead to show us that heroes can die and not come back to make sure when our heroes are fighting Thanos with the infinity gauntlet that some of them might not mke it out of Avengers: Infinity War. Which raises the stakes and put the audience at the edge of there seat.