The tone of the MCU has always been pretty light. Even with Earthâ€™s fate hanging in the balance, you never get the sense thereâ€™s any kind of real danger. Sure, Iron Man 3 scratched the surface of Tony Starkâ€™s struggle with PTSD, and Age of Ultron had a few nightmare sequences, but Guardians 2 really upped the ante.
Every character in the movie, save for Baby Groot, had to confront their demons. As I mentioned above, Rocket acts the way he does so he never truly feels close to those around him. Gamora and Nebula, meanwhile, had to work through their childhood rivalry, which was forced upon them and encouraged by a diabolical Thanos.
In addition to the individual struggles, the film had a few really dark twists. As Ego reveals his plans to Peter Quill, Gamora and Nebula find a tomb filled with skeletons. We soon find out that Ego was literally killing his spawn because they served no purpose.
Speaking of which, Ego reveals he killed Peterâ€™s mom because he was becoming too attached. Thatâ€™s messed up. There were several emotional arcs like this, which have been missing from other MCU films. For once, the stakes were high, and it finally felt like these characters mattered, and werenâ€™t just vehicles to move the plot forward.