In the early stages of the Marvel Cinematic Universe, Marvel became notorious for never letting a character die. Iron Man died in Avengers, but not really. Loki died in both Thor and Thor: The Dark World, but not really. Bucky died in Captain America: The First Avenger, but not really.
When Quicksilver died in [The Avengers: Age Of Ultron](tag:293035), well, he stayed dead.
Though he and Scarlet Witch both started off as villains, Pietro Maximoff ultimately gave his enhanced life to protect Hawkeye. This was a sad moment for all viewers, whether you liked Quicksilver or not, because this was the first time where Marvel killed off one of their major heroes (for real).
The situation was made even sadder when you see Scarlet Witch's reaction. After their parents died, Wanda and Pietro were the only family that each other had. And when Pietro was shot down, Wanda snapped and used her powers to destroy all of the Ultron drones and ultimately win the Battle of Sokovia.
In Captain America: Civil War, they never explicitly acknowledge Quicksilver's death in the previous film, even though Scarlet Witch has a much larger part in this film. However, he gets a bit of a tribute moment that you may have passed over when you saw the film.
In an early scene in the movie in the Avengers compound, Steve Rogers goes to Wanda's room to discuss events that happened at the beginning of the film. As they are having a heart-to-heart discussion, we can see a few knick-knacks and decorations to give Wanda's room some more personality. One of these decorations is a picture on her wall of a young boy with blonde hair.
Once you see that kind of picture in Wanda's room, it's pretty clear to tell that the picture is of a baby Pietro Maximoff. After Marvel made such a big decision to kill Quicksilver in Age of Ultron, I'm glad that they didn't just gloss over it.
Captain America: Civil War was a fantastic movie with so many amazing moments, and it's likely that quite a few clever Easter Eggs (like Pietro's baby picture) slipped by without us noticing.