The Marvel Cinematic Universe is full of committed and experienced heroes, but many of them share a lot of heroic elements. Now with the franchise moving into a new phase, one of the most engaging potential characters that could be introduced would help make for an interesting dark new threat to Ant-Man.
With that said, let's breakdown who Eric O'Grady, aka the Irredeemable Ant-Man, is and why he would be a perfect addition to the MCU.
WHO IS THE IRREDEEMABLE ANT-MAN?
Eric O'Grady was a low-level agent of SHIELD who, after being caught in the chaos of Wolverine: Enemy of the State, ended up stealing the newest prototype of the Ant-Man suit. But unlike many of the heroes of the Marvel Universe, Eric doesn't turn out to have much of a moral compass. Instead, he's actually a craven, perverted scumbag. Using the stolen suit, Eric ended up creating a false identity and a superhero persona called the Slaying Mantis and trying to hide from the authorities while only protecting attractive women as a veneer to try and take them out.
O'Grady finds work with Damage Control and ends up slowly falling in love with one of his co-workers, Abigail aka Visioneer. Slowly, Eric showed that he did have the potential to be a good man -- albeit still an opportunistic jerk who had to manipulate and lie to avoid jail time for his past actions while stealing the suit. Eric ended up as a part of the Initiative, and eventually even was recruited to the Secret Avengers. While on a mission, however, Eric was beaten to death while saving a child. Later, an LMD copy of Eric was released, becoming the more morally ambiguous Black Ant and becoming a partner in crime to Taskmaster.
WHY THE IRREDEEMABLE ANT-MAN IS PERFECT FOR THE MCU
The MCU is largely full of straight-laced heroes at the moment. Many of the heroes of the franchise have either overcome their past failings to become better people. It's a common thread for many of the films in the continuity. However, Eric O'Grady pushes enough buttons and complicates enough things to really put the other heroes on edge. He would make for an interesting question about heroism and the people who are capable of it, almost an anti-Captain America. To put it simply, Eric is proof that bad people can genuinely do good things sometimes.
Because make no mistake, Eric O'Grady is a bad guy. He only ever got ahold of the Ant-Man suit because he accidentally pushed his friend into the way of a laser blast that killed him. He even hooked up with his friend's girlfriend and got her pregnant, while refusing to be a part of the baby's life out of the sincere belief that the child would be better off without him. Eric is a scumbag, and he knows it. But there is a genuine arc to the character and his attempts to at least try to be better, all building to him technically being killed while doing a genuinely noble act.
His introduction would create a darkly familiar version of the typical archetypes of the franchise and give the MCU a new perspective to bounce off of the other characters. Eric could become the Guy Gardner of the MCU, forging just as many rivalries and hatred as loyalty. It could even be used to highlight people with similar mindsets, and try to show them learning to become better people by showing how bad they could be. He'd make an easy comic figure as well, especially if juxtaposed against someone like Captain Marvel who would have no patience for his antics.
On top of that, Eric's connections from the comics present a lot of interesting ideas for Ant-Man and his associated characters. Eric became Ant-Man shortly after the demise of Scott Lang during Avengers: Disassembled. Cassie Lang also became Stature during this time, and the pair ended up getting into a massive brawl after he insulted Lang. With Cassie already introduced into the MCU (and conveniently aged up thanks to the events of the Snap), it's likely that she'll become Stature if there's a potential Young Avengers project. Eric could make for a great contrast to her as she grows and tries to define herself. Eric would even just make a fun rival for Scott. In a way, Eric is all the things people assume about Scott, but real. He could be a great rival to Scott and highlight just how far the current Ant-Man has come by becoming a hero.
There's also the potential of his current role in the comics being explored. Taskmaster will make his debut in the MCU in the upcoming Black Widow, and if he survives the events of the movie then he and Eric could become potential allies -- or even members of a possible Thunderbolts film. There's a lot of potential places Eric O'Grady could take the MCU if he was introduced, and should give the producers at Marvel Studios an idea of what could become the future of Ant-Man in the franchise.