Thunderbolts

The Thunderbolts was a group of former supervillains that attempted to turn over a new leaf and become villains. However, as time moved on, the leader Citizen V announced it was all a subterfuge and they were the new Masters of Evil. Citizen V was revealed to be Baron Zemo and was brought to justice with some of its members, including Hawkeye getting less sentences and even a pardon later for their efforts to stop their former leader from his evil plans.

History
Baron Zemo looked at the acclaim and acceptance that people gave hero groups like the Fantastic Four and Avengers. They were given all sorts of clearances and could almost act above any suspicion no matter what they were doing. It gave him an idea.

Baron Zemo began recruiting his own team of heroes, starting with Moonstone and Fixer. He filled them in on his plan and convinced them of the brilliance of it. Then, as Citizen V, he started recruiting some flunkies who would help with his cover and be easily manipulated. He chose Goliath (Atlas), Screaming Mimi (Songbird), and The Beetle (MACH-1). They all chose new names and costumes, and Citizen V convinced them they were starting off a new life as Superheroes.

The Thunderbolts appeared on the scene, helping to fight against HYDRA, AIM and other villainous groups, fighting crime and living what seemed to be a very open lifestyle of reformed criminals. Public opinion was mixed about the group, with some untrusting but others willing to believe they could have turned over a new leaf. Early on, there were some misunderstanding clashes with the Avengers and other heroes, but each time it seemed that the Thunderbolts were actually exactly what they seemed to be, heroes.

Only Fixer and Moonstone knew who Citizen V actually was and that while he was helping stop the crimes of others, he was gathering information and intelligence to make himself unstoppable. Not to mention the occasional missing goodie or two that could be blamed on the criminals they were helping catch. Gradually over the months, the Thunderbolts became more and more accepted as a group of heroes.

Suspicion stayed in some hearts though and it lead to a rift in the Avengers as Hawkeye grew more and more upset by attitudes of people that couldn't believe villains could reform. He came out publicly on many occasions supporting the Thunderbolts in their attempts to do good. Finally, after hearing about a plot to infiltrate and spy on the Thunderbolts, he quit the Avengers and went to join the Thunderbolts.

Citizen V was suspicions about him, but couldn't think of a way to refuse without raising suspicions. In the end he decided that Hawkeye would be easy to manipulate and let him join the ranks. As a villain who had turned good in the past, Hawkeye became a figurehead for the Thunderbolts, a symbol for them to rally behind.

Just because Hawkeye had joined them didn't mean that investigations into the Thunderbolts had stopped however. Zemo could feel the plan about to come apart as SHIELD and the heroes started to compile evidence of his activities. He decided it was time to throw the veil aside and so he publicly broadcast that the Thunderbolts were really the new Masters of Evil, including Hawkeye. He figured that would force the others to throw in with him, but he didn't figure on the influence of Hawkeye.

As Baron Zemo tried to lay out plans for conquest using the knowledge and stolen technological times he had gathered, Hawkeye ordered him to surrender and clear the names of the others including himself who didn't want any part in the plans. A battle ensued with Moonstone and Fixer helping Zemo beat down Hawkeye, Atlas, Songird, and MACH-1. Zemo was about to end Hawkeye's meddling forever when SHIELD and the Avengers showed up to arrest all of them. Hawkeye was given a chance to claim that he had just been spying on the Thunderbolts for the Avengers to keep himself out of prison, but he chose instead to join the Thunderbolts in prison.

Because of the fact that they didn't know about the thefts and espionage crimes that Moonstone, Fixer and Zemo were committing, even while they aided them, Hawkeye, Atlas, Songbird, and MACH-1 were all given light sentences. These in turn were all later pardoned for their help in trying to apprehend the other three, and the quartet were released from prison on the condition that they never return to crime.