The film Black Widow throws light on Natasha and Clint/Hawkeye’s iconic Avengers: Endgame moment. After Thanos wiped out half of humanity, the remaining Avengers moved on with their life. However, Natasha aka Black Widow devoted her time to find a way to reverse it all while she led a team and resolved threats anywhere in the universe, including Hawkeye’s new vigilante avatar.
It is when the Avengers realise they had a chance to reverse the snap and kill Thanos along the way, Clint and Natasha bravely take on their mission in Vormir. To get the Soul Stone, however, either Black Widow or Hawkeye had to be sacrificed, “a soul for a soul”. Both of them wanted to sacrifice themselves. Natasha’s sacrifice would mean fulfilling her wish to bring everybody back, while for Clint, it would redeem him after he led a life as a vigilante.
Hawkeye had spent the last few years assassinating the criminals who had survived the snap, while his family could not. As a matter of fact, he joined the time heist only in hopes of reuniting with his family. So, why would he decide to just give up his life that easily? Perhaps, Hawkeye wanted to actively save people this time, but it may also be because he learned about the events that unfolded in Black Widow. Knowing that part of Natasha’s intention to sacrifice herself is to erase the red in her ledger, Hawkeye would never want to just stand there and watch. After all, he even told his long-time friend and partner that her “life’s worth ten of mine”. He could have been sincere about saving lives, or perhaps he was aware of what all happened in the film ‘Black Widow’.
In Black Widow, Natasha had a mission to assassinate Dreykov to defect to SHIELD. Even though she knew it would kill his daughter Antonia, Natasha went through with it, believing it was necessary to take down the Red Room. However, both father and daughter survived, leaving Antonia injured. This was followed by Antonia being controlled by a chip, turning her into the Taskmaster. It fueled Natasha’s guilt because she felt that the girl was suffering because of her, so she decided to sacrifice herself on Vormir to atone for her past.
On the other hand, Clint must have known about her extended family and thought that she was needed by a lot of people. Hence, he decided it was more important to save her.