Sometimes I think everything after the first Avengers movie is just some out of control fanfic of a couple of fans that had the money to hire the actors.
"Ohhh we want Bucky Barnes back let's turn him evil."
"Also we totally need an X-men crossover let's throw in Quicksilver and Scarlet Witch."
"We should destroy Asgard and have Thor have an evil sister!"
"Yessss let's break the hammer too, and give him a total makeover!"
"And then we can hold a Civil War so people stop shipping Stony!!"
"AND WE SHOULD KILL LOKI! Done."
"No you can't kill Loki I'm bringing him back."
"STOP IT! LOKI MUST LIVEEE!"