Arguably the most hardened member of her team, an assassin-turned-good with a dark past, one which she managed to overcome through both self-discovery and newfound friends whom she now calls a family. This description could fit very well for Nebula, as much as it could fit for Natasha Romanoff, Black Widow herself. Avengers: Endgame saw that, and gifted us with parallel character arcs for them.

These two have their own highlights in Marvel Comic’s legacy, and both were important in certain moments of the comic’s history, but neither of them are of pivotal importance to the overall Earth-616. That is, in the comics, they are far from the importance of a Reed Richards, Charles Xavier or Stephen Strange. Therefore, in the Marvel Cinematic Universe, they could have easily been completely forgotten. If not forgotten, both could have certainly been nothing but supporting characters for the Guardians and the Avengers.

Luckily, their MCU versions were given much, much more to do than one would have expected in 2010, when Natasha first came into the continuity as a supporting S.H.I.E.L.D. character for the crowded Iron Man 2, or in 2014, when Nebula was presented as an antagonist in Guardians of the Galaxy. No one would have guessed that, so many years later, both would have been key pieces in the culmination of the whole MCU.

First, let’s go on a quick trip down memory lane. As of now, we don’t have a lot of detail on Natasha’s past, but we know the overall story of her life. Born in Russia, she was recruited to become a world-class spy and assassin for the Russian government. She was trained, taught, tortured and tested in order to be the best weapon she could be for her masters. Her life turned around when Clint Barton was sent to kill her but decided to spare her life and recruit her to work with S.H.I.E.L.D., where she eventually would end up joining the Avengers. Through her new found life and relationships, she discovered a version of herself that she never thought could exist after all she had done. A member of a family, a protector, a friend.

The same goes for Nebula. We may not know the exact circumstances of her earliest days, but we know she was recruited at some point to become a universe-class assassin for the Mad Titan, Thanos. She was also trained, taught, tortured and tested in order to be the best weapon she could be for her master. Her life turned around when she and Gamora decided to stop fighting and be the sisters they were always meant to be. She would end up becoming an ally of the Guardians of the Galaxy, and through her new purpose and relationships, she found a version of herself that was previously thought not to exist. A member of a family, a protector, and a sister.

Thanos’ quest for the Infinity Stones had cost both Nebula and Natasha their closest people. Gamora literally died for the Soul Stone, leaving Nebula alone to finish the mission they started together. The loss of his family turned Clint into someone else entirely. He may not have died, but he became a mafia-killing monster and disappeared for five years. When Thanos snapped his fingers, Nebula lost most of what was left of her family, and so did Natasha. Therefore, they had very personal reasons to get involved as much as they could in undoing his deeds.

But enough about their pasts. Now that we’ve established their similarities, it’s clear that Christopher Markus and Stephen McFeely, the screenwriters behind Avengers: Endgame saw all of that and decided to put both at the center of the movie. Sacrifice for the greater good is probably the core of the film, and both Nebula and Natasha did exactly that to protect their newfound families and the whole universe.

The first thing we see after the Marvel Studios logo is Tony Stark and Nebula playing and trying to find something to do as they await a very likely death. Alone in the depths of space, no one was there to tell Nebula what to do or how to behave according to her new reality. She chooses, out of the kindness of her heart, to treat Tony as a friend, to put him into “bed” when he passes away on the floor, to give him her part of the food and even to feel bad for his state. All things that she never would have been able to do a few years prior. When they return to Earth, she even holds Rocket’s hand as they mourn their losses.

Meanwhile, Natasha and the survivors of the Decimation are trying to understand what the hell happened when Thanos snapped his purple fingers. After a melancholic mission in which the Mad Titan lost his head, five years go by. In a post-snap world, the only original Avenger that chooses to remain working full-time as a protector is her. She mourns for the loss of so many people she cared about, while also finding the strength to lead her own version of the Avengers. She even allows herself to cry after getting news of what Clint has become. The spy she used to be, both for the KGB and for S.H.I.E.L.D. would never have taken this path.

Eventually, the film takes us to Japan, where Natasha has to convince Clint to leave his murderous, dark Ronin days behind and join the good guys again. It’s no coincidence that this is exactly what Clint did for her, so many years ago, when he convinced her to leave the KGB and join S.H.I.E.L.D, leaving her dark days behind. Traveling back to 2014, Nebula has to convince her sister to leave her days as a servant of Thanos behind and help the good guys undo his genocide. Again, it is not a coincidence that Gamora did the same for Nebula in the past, as the script clearly draws a parallel here.

Still, in 2014, the quest to bring her family back together took Nat to Vormir, where she is greeted by the Stonekeeper as “Natasha, daughter of Ivan”. In the depths of space, during a mission to save the universe, she is purposefully told her father’s name, a man she apparently never met and whose name was unknown to her up until now. He may or may not have had something to do with all that the Red Room did to her. Meanwhile, Nebula, after dealing with her father’s death earlier on, has to face his genocidal persona once more. She comes face to face again with the man that tortured her for so long, but not in a weak, pitiful state as he was when the movie started, but at the height of his power pre-stones. The time heist forces both to deal with their pasts.

And so it happens. After a marvelous character arc developed along seven films, Natasha Romanoff is willing to let go of her own life to bring back the family she learned to love. As she lets Clint’s hand go, we witness the end of a journey that turned a murderous villain into a sacrificing hero. It’s the perfect end for Nat, even though it’s a painful one for us to watch.

Nebula’s arc in the MCU, however, is not yet complete. She teams up with her sister to try and stop Thanos from killing not only half but the whole universe and starting another one as he sees fit. Seeing her old self act the way she used to, Nebula realizes it wasn’t one thing, one moment or one conversation that made her change. Upon watching herself in the past, she learns that it was herself who slowly realized (with Gamora’s help, of course) that she could be different.

After so many similarities, this is probably the greatest difference between her and Nat. While the Black Widow was convinced by Clint to join S.H.I.E.L.D. and then mentored by Nick Fury to change and become someone else, Nebula did it on her own. The improvement of her relationship with Gamora and her finding of a family in the Guardians was not due to external factors, but internal ones.

That’s why, unlike Natasha, she didn’t have to sacrifice herself to save her family, but instead had to literally kill her old self. She knew the Nebula from 2014 wouldn’t stop trying to please Thanos, and therefore nothing she could say at that moment would turn her. In a beautifully metaphoric moment, she shoots her old self and proceeds to fight alongside Earth’s Mightiest Heroes against her father.

Avengers: Endgame gives us a beautiful arc for these two characters, establishing parallels between them, but leaving them in different places. While Natasha had grown as much as she could have, becoming a hero in the process, Nebula has only now abandoned her past once and for all and is freer than ever to travel alongside the Guardians and deepen her relationships to her new family. That’s the end for Nat (though we will be seeing more of her past soon) and a new beginning for Nebula.

The MCU is a vast landscape, richly populated by the most interesting supporting characters pop culture can give us, and we should all appreciate that. This movie, after all, is all about appreciating the decade of movies that Marvel Studios has given us.