WARNING: The following article contains spoilers for Black Widow #1 by Kelly Thompson, Elena Casagrande, Jordie Bellaire and VC's Cory Petit, on sale now.
In the new Black Widow series, Natasha disappeared after a mission she undertook with Captain America and Hawkeye. When Hawkeye discovered she was still alive and in San Francisco, he called up Winter Soldier to help him investigate and if need be save her. However, this is all quite strange considering that Clint Barton lied to his friends and betrayed their trust in his last appearance.
In Matthew Rosenberg and Otto Schmidt's Hawkeye: Freefall, Clint helped arrest The Hood only to watch Mayor Wilson Fisk order the villain released from jail. Soon, Ronin was back, and almost all of Clint's friends believed it was him breaking laws to bring people down on the streets.
However, Clint denied everything. He lied to Falcon and Winter Soldier and went as far as stealing S.H.I.E.L.D. time travel tech that allowed him to show up twice in the same fight. Clint showed up with his friends as Hawkeye and battled himself as Ronin, clearing himself of the accusations. He lied to Spider-Man, asking him to trust him as a friend. Hawkeye lied to Black Widow, even though she never bought his lies for a second, and to his ex-wife, Mockingbird. Clint then did the unthinkable and lied to the man he has traditionally looked up to, Captain America.
It got worse when Clint started working with a minor who was previously a criminal hacker. The assassin Bullseye killed the teen in an effort to get to Hawkeye after murdering a Skrull that Hawkeye forced to impersonate him. Captain America approached Ronin, thinking he was Clint when it was Bullseye in disguise. Bullseye immediately attacked, taking the Avenger by surprise and putting him in the hospital.
In Black Widow #1, Hawkeye is not only back in the role of a hero, but is working with Captain America. Black Widow was in Hawkeye: Freefall, meaning that those issues took place before her disappearance. By this logic, Captain America is working with Hawkeye and Black Widow on this mission after Clint's actions in Hawkeye: Freefall.
It would be understandable for Captain America to hold a grudge against Hawkeye, especially considering the fact that Clint's lies were a large part of the reason he ended up in the hospital. Still, Captain America, and he knows Clint better than anyone as the two of them have a long and storied history together. In addition, Clint did the right thing at the end of his series, opting to ultimately operate within the confines of the law and not kill anyone. Perhaps Captain America is able to see that past Hawkeye's gruff exterior and reckless behavior he really wants nothing more than to be a hero just like the Captain, and that made him not only worthy of the Star-Spangled Avenger's forgiveness, but also worthy of his trust.