Origin

Connor was old university friends with Tony Stark, Reed Richards, Victor von Doom, Bruce Banner, and Henry Pym, and they formed a group dubbed the Knights of the Atomic Round Table as they all were involved in their own scientific pursuits to better mankind. Close friends with Tony, Connor would be nicknamed "Rebel" due to his devil-may-care and almost suicidal tenancies. His reckless attitude would match his devotion to helping Tony create his suit of Promethean Armor, a self contained life-support/battle suit, despite the fact that the Russians had supposedly beat them to it with their invention of Titanium Man.  
While they were working on the Prometheus Armor, Victor arrived and casually told them that they wouldn't get very far with their unscientific project. Rebel took this as an insult and vowed to see the armor's development through to completion. 
As the armour neared completion, Rebel's girlfriend would leave him, finding his reckless behavior too much, wanting to be with someone more well grounded like Tony Stark.
 

Mayor Story Arcs

Promethean Armor

Afterwards, when Victor broke up and the Fantastic Four originated, Rebel stuck with Tony. He became Tony's employee, but still remained his closest friend. Together, the two of them endeavoured to break the barriers of science.
  
One night after a series of tests on the Promethean Armor, when Tony was exhausted from non-stop working and had fallen asleep, Rebel took this chance to slip inside the Prometheus armor and give it a test flight, he snuck out of Stark International's compound, he got away without Tony knowing. Rebel flew over to Russia to test out it's superiority against the Russian's Titanium Man. After entering Russian airspace, Rebel was immediately attacked by the Titanium Man, unfortunately Rebel's armor was not developed to the point that it could handle Titanium Man's attacks, he was issued a humiliating defeat. After showing his superiority in combat, the Titanium Man would let Rebel live and report back to his country and have them shelve their inferior invention. Rebel would quickly return to the United States and tell nobody of his humiliating defeat.
 

Seeming Death

Later, when he was test driving the armor another day, things did not go well. The armor's circuitry suffered an overload, which caused it to blow up, seemingly killing Rebel. But  Hydra dug him up and restored him to life. They made cybernetic improvements on Rebel and gave him a new armor, which was controlled by Hydra. Then they sent him to kill Tony Stark.   
 

Rebel came outside Stark's window and shot a blast, which hurt  Happy Hogan. Later when he faced  Iron Man, he had a brutal fight with him. In the end, Iron Man managed to override Rebel's armor software and defeated him. Tony lifted Rebel's mask and found him in a pathetic state. Immediately, he carried Rebel to the FF lab. Tony jacked himself up with Rebel to keep him alive. Rebel recounted to Tony, all his past experiences as his friend. But Reed Richards severed the cable connecting Tony and Rebel. He spoke out the truth: Rebel would live only for a few hours more. Rebel resolved to die likea hero. 
 
Iron Man and Rebel attacked Hydra's base. They defeated Titanium Man and Crimson Dynamo. Rebel switched armor with Tony. They broke into Hydra's base. Rebel spent the full power of the Iron Man armor in trying to defeat  Mandarin. He died in Tony's arms.