X-Men Apocalypse spoilers ahead!
For me, Eriks metal X was one of the best things in the whole film. I mean, as the fight started it soon became pretty clear that at some point Erik would switch sides again (as if it wasn’t already clear at the beginning of the movie ;)). And it was clear that it would be through memories of the people he cares about, Charles, the Xmen, everything that had happened so far (because that’s just how Erik is, these are the things he cares about underneath all this rage, right? That’s the REASON for all his rages - that he cares so much about the people he loves).
But with Quicksilver on board I also imagined that the final thing that would lead to Erik changing his mind would be Peter revealing that he’s Eriks son and he therefor still has family. But to my surprise that didn’t happen. Instead they used only Erik’s memories and flashbacks of Charles show why he changed his mind. And if that wasn’t telling enough, Erik used his powers to protect Charles WITH A GIANT METAL X! I was absolutely stunned by that. The meaning behind this. The X standing for Charles, the X-Men, Charles’ dream and ideas, his view of the world that Erik finds so hard to accept and Erik used that symbol as a protection and a warning against Apocalypse and on the other hand letting Charles know that he still cares for him.
Long story short, I absolutely loved this scene!