While the entirety of Marvel Comics’ Civil War event contained a multitude of interwoven storylines of betrayal and deceit, one aspect of the event involving a forgotten Avengers traitor is easily Civil War’s biggest missed opportunity. Nearly every character within the Marvel Universe found themselves fighting a superhero civil war after Iron Man backed a proposed law that would force superheroes to register themselves with the government, with dissenters locked away in an inescapable facility. Captain America strongly opposed Iron Man’s efforts and formed a team of heroes to stand up to Stark and his team, who were working to enforce the Superhuman Registration Act. During the conflict, one superhuman became a spy who was eventually found out by the enemy, but other than the immediate moment of that revelation, the subplot was never explored further.
In Civil War #6 by Mark Millar and Steve McNiven, Captain America and his team are coming up with a plan to free all of the incarcerated heroes and villains that were arrested under the Superhuman Registration Act. When Cap’s team arrives at the Prison 42 facility, they are met by Iron Man and his army, who are there to stop Captain America’s forces and throw them in prison alongside those they were trying to free.
Iron Man knew Captain America’s team was coming to the prison because he had a mole on Cap’s side who was feeding Iron Man information. The Avengers traitor was Tony's former West Coast Avengers teammate Tigra, and while she was responsible for Iron Man intercepting Captain America’s army at the prison, it was all a part of Cap’s larger plan. Captain America reveals in this issue that he knew Tigra was a spy all along, and he wanted her to tell Iron Man about this plan so he could manipulate their final clash in his favor. After this revelation is made, Tigra doesn’t answer for her betrayal as the story moves into the final fight then ends with Captain America’s surrender. However, what the book does go into is the further complexity of using spies during wartime, as Captain America also reveals that he had an informer on Iron Man’s team as well, one that Stark was completely unaware of until the big reveal.
The reason Captain America wanted Tigra to tell Iron Man about his prison break plan was because he wanted Iron Man’s full forces there when they released the prisoners. Captain America was able to pull off the prison break after his spy, Hulkling, used his shape-shifting abilities to pretend to be Hank Pym, informing him of Tigra's defection and unlocking the prison. Hulkling releases everyone, which grows Captain America’s army exponentially and leads to the final showdown Captain America had been planning all along.
It's a fun double-bluff that puts Tigra and Hulkling at the heart of each camp, but readers never get to see the process behind their efforts. Instead, the two are only revealed as an explanation for how the final showdown turns out, despite the fact that they pose some of Civil War's most fascinating questions, being heroes who aren't just fighting for what they believe in, but actively deceiving former friends and leading them into a trap. The event's many tie-ins dug deep to show different aspects of the war, and yet while the spycraft shapes the narrative until its final moments, it gets almost totally ignored.
Tigra was rewarded with a place in Iron Man's Initiative, but never answered for her treachery in a specific manner. Civil War was a story that pitted friend against friend, and yet despite Tigra going further than almost any other hero, Marvel all but ignored her contribution. It's not unheard of for Marvel to revisit old stories from a new perspective (it's even done it with Civil War before), so thankfully there's always the chance fans will one day get a flashback to Tigra's role in this huge event and witness the tension of a conflicted double-agent working behind the scenes to betray the Avengers.