The Black Widow assassin Clint faces is none other than Yelena Belova (Florence Pugh), Natasha’s surrogate little sister who reconnects with Nat during the events of “Black Widow.” Yelena originally has a bit of a chip on her shoulder when it comes to her heroic “big sister,” because Nat managed to leave the Red Room behind and she didn’t. However, by the time the movie wraps up, the two are on pretty good terms, and it’s clear that they care about each other.
If you’re wondering why such a close member of Nat’s “family” is hunting down Clint — who, for all intents and purposes, was Natasha’s closest friend in the whole, wide world – there’s a reason for that, as well. In “Black Widow’s” post-credits scene, Yelena and the mysterious Valentina Allegra de la Fontaine are seen mourning Nat after her death in “Avengers: Endgame.” Val, who clearly has ulterior motives that Yelena is missing, tells Yelena that Natasha’s death was Clint’s fault, which presumably sets the young Black Widow on a path of revenge that finally escalates to kicking and punching in “Hawkeye” Episode 4. It remains to be seen whether Clint is able to reveal the truth to Yelena, and whether she’ll believe him.