The problem with Clint Barton becoming 'Ronin' despite the fact he was killing people with his arrows as 'Hawkeye' is the same problem people should have with a police officer or soldier deciding to become a vigilante and kill those he considers criminals*.
Hawkeye was introduced as a reluctant villain in Tales of Suspense #57 (Sept. 1964). After two more appearances as a villain in Tales of Suspense #60 and #64 (Dec. 1964 and April 1965), Hawkeye joined the ranks of the Avengers in The Avengers #16 (May 1965).
In the comics, Hawkeye adopted the Ronin identity at one of the darkest times of his life. In the modernized Ultimate universe, just as in the MCU, the trigger was the death of his entire family. Hawkeye turned into a Punisher figure, seeking out criminals and murdering them in his own form of justice.
In the wake of the Snap, Barton lost his family and went onto a grief-fuelled rampage against criminals for five years as a vigilante known as Ronin. In 2023, Barton was convinced by Black Widow to return to the Avengers in attempt to resurrect the victims of the Snap.
As in comic books, Clint's grief and trauma led him to leave behind his Hawkeye identity to become Ronin, though in the MCU this is due to the loss of his family as a result of Thanos' Snap.
The Ultimate version of Ronan the Accuser is the son of Thanos, and is a part of his empire. He is ultimately defeated by the Thing. In the series Hunger, another version of Ronan called Ro-Nan is married to Esa-La and have a son named Dra-ta.
Natasha Romanoff was born in the Soviet Union as Natalia Alianovna Romanova (Наталия Альяновна Романова). Although her exact parentage is unknown, it is rumored that she is related to the late Romanov dynasty—the former rulers of Russia—but those claims have so far been unproven.
The 2014 comic run, Hawkeye: My Life as a Weapon by David Aja and Javier Pulido revealed that Clint's deafness began due to abuse suffered during childhood. Neither of those backstories is adapted into Clint Barton's MCU series, which establishes that Hawkeye is deaf as a result of repeated trauma on Avengers missions.
Of course, he's one of the exceptions as he turned evil even before becoming the Avenger. Bucky was a hero who fought alongside Steve Rogers in World War Two. But when he was captured and brainwashed, he became an assassin known as the Winter Soldier.
Barton was then taken into the compound and locked up in a glass cell, with S.H.I.E.L.D. agents standing watch outside. While he was sitting on the floor, Hank Pym flew down to him and injected him with a toxic substance that killed him.
As a result of the alienation he experienced from his friends, Hawkeye was lost and confused without the necessary support needed to cope with the death of his family.
Earth's Mightiest Marksman, Clint Barton employs a devil-may-care attitude and mastery over one of civilization's oldest weapons as the Avengers' ace archer, Hawkeye. A mainstay of the hero team, Barton brings along an undying heroic spirit and the ability to hit any target.
The man who would become known as Hawkeye was born Clint Barton. Orphaned at an early age, he joined the circus and apprenticed himself to the Swordsman, a performer who specialized in tricks with blades. After he discovered the Swordsman stealing from the circus, the two fought, and Barton was left for dead.
Filled with rage, Wonder Man attacked Hulk, but after his body was pierced during the fight, Wonder Man exploded in a gigantic meltdown. Mockingbird and Hawkeye had fled the scene to safety, but Hawkeye, feeling bad about leaving his friends behind, turned to see the explosion, which rendered him blind.
If Valentina is putting the Thunderbolts together covertly or illicitly, Clint Barton is the only remaining ex-Avenger who could potentially notice and intervene. And Hawkeye is far more dangerous than he appears to be, which Val respectfully acknowledges by taking steps to eliminate him.
A simpler explanation is simply that the watch is valuable and highly sought after, and Fisk wasn't interested in acquiring the watch via a purchase, so he sent his men to a black-market auction to steal it.
Black Widow's first romantic relationship was with Nikolai, a soldier she met while both were serving with the Russian Army during WWII. The young soldier had no backstory, but Natasha and Nikolai fell in love and eventually married.
Did Hawkeye love Black Widow and did she love him in return? While never explicitly stated in the films leading up to Avengers: Endgame, Natasha Romanoff and Clint Barton have a romantic connection in their relationship, though they couldn't consummate it for various reasons.
Natasha chose to be the sacrifice and so, Romanoff was 39 years old when she died, but the time travel in Avengers: Endgame creates a little bit of a complication. Romanoff and Barton used the Quantum Realm to journey back to 2014 so they could beat Thanos (Josh Brolin) to the Soul Stone by 4 years.
Yondu Udonta was a survivor above all else. He lived through his time as a Kree slave and become a Ravager captain. Yondu had a soft side and decided to keep Terran child Peter Quill on his ship instead of turning him over to his murderous father.
