So, long story short - Jack Harrison is some whacko that started a civvie vigilante group called Stars and Stripes. Some sort of Captain American fanboy club that helps citizens, makes up foot patrols, a 'real world super hero' movement type concept. In conjunction with this civvie group, he had his back broken and was bound to a wheelchair. He was arrested and sentenced to 10 years, federal prison, in connection to a criminal organization known as Kobra. En route to the final prison where he was to serve, the transport is hit by Kobra raiders and Jack Harrison is one of the 'freed' individuals. Along with other Kobra members also being transported to that prison.
Jack Harrison was recently scene, by few who might actually remember him, with Vance Astrovik, that 70s era astronaut returned to earth with stories of space adventures with some job called Guardians of the Galaxy. Also, he no longer needs a wheelchair it seems.
His alter ego (secret identity) - Jack Flag, a stars and stripes caped crusader, has done a few vigilante esque hero calls but nothing to stand out as a regular super hero type. Not enough to really be recognized even save by a few people that might have seen him. Jack Flag has been showing up about as long as that Jack Harrison has been spotted talked with Vance recently.