WARNING: The following contains major spoilers for Devil's Reign: Moon Knight #9, available now from Marvel Comics.
Since his debut, Moon Knight has always been one of the Marvel Universe's most unpredictable vigilantes. Where Spider-Man upholds a code of peace and fairness in his heroism and Daredevil tempers his brutality and emotions when he can, Moon Knight rides the wave. Now, this has made him often unchecked, overly violent and totally excessive in his brand of vigilantism. And in Devil's Reign: Moon Knight #1 (by Jed MacKay, Federico Sabbatini, Lee Loughridge and VC's Cory Petit), his dark side enters the moonlight once again to remind readers why he's so dangerous.
With Wilson Fisk the Mayor of New York City, he has instilled a new order that outlaws all those that wear a mask in the city. As a result, many heroes have been incarcerated for being against the law. This included Moon Knight, who was seemingly apprehended by some of Fisk's Thunderbolts, government-sanctioned villains, and heroes turned city deputies. Now with Marc Spector apprehended, he quickly made a name for himself in the prison when he picked fights with some criminals. In doing so, he also earned a spot in an underground fight club that allowed him a shot at the title, battling it out with many other prisoners.
While in prison, Marc explains to his cellmate and the reader that being inside the prison for too long was bad for his health. But in reality, what he was explaining wasn't that incarceration made him sick. In actuality, it awakened his dark side, something he hadn't tapped into in years when he would brutally main criminals to send a message. While in prison, he was primarily surrounded by the criminal element, and the urge to exact justice in a particularly brutal way was only just out of reach. To better explain why Marc's most dangerous qualities should be a concern, he used pain as a metaphor for why he keeps fighting.
According to Spector, "...pain's what tells you that you're alive. Everything's got a cost. Pain is life's." With each battle, Spector gains yet another scar to add to his collection along with another lesson in pain. However, his belief also showed that, deep down, Marc Spector is still a very dangerous man. He has only ever seen the worst in people, so much so that his actions have alienated him from other notable heroes. That said, rather than use that rage and violence for evil; he has made it a point to direct it towards those that aren't good people.
It's revealed in the issue that the only reason he was incarcerated was to get close to Man Mountain Marko and threaten him to never go after his ex-wife and daughter, per his ex-wife's request. However, when Marko ignored his threats, Marc tapped into his wild side and gouged out Marko's eyes with his thumbs, reminding him that he told him he'd never see them again. It was one of the darkest moments for the character since he cut the face off of Bushman in the 2006 Moon Knight run by Charlie Huston and David Finch.
Moon Knight is a hero, but he still represents a necessary evil that is used to ensure the worst of the worst think twice before harming others. In recent years, Moon Knight has shown a tapering of his aggression towards criminals. While he's still brutal, he's less hands-on with his means of punishment. But Devil's Reign: Moon Knight showed that while Marc has managed to control his more violent urges, he can still turn it on like a switch, whenever needed. As a result, his control, or lack of, with his rage once again proved why Moon Knight is still one of Marvel's most dangerous heroes.