Halcyon debuted in Iron Man #1 by Christopher Cantwell and CAFU.
Major Story Arcs
Halcyon first met Tony Stark after the events of Iron Man 2020. Stark was looking for a more simple life, including street racing a stock car against experts like Halcyon. After months of occasional street racing, Stark needed a favor he thought Halcyon could help with. He needed Halcyon to get a team together with his connections in the underground scene.
Between his mutant ability and expert mechanic talent, Stark invited him as well. Halcyon was able to put that talent to the test when Korvac broke Iron Man's neck while he was in his armor, and Halcyon needed to retrofit the armor to work as a rudimentary brace.
Together, the team head in to space chasing Korvac and his band of Iron Man rogues. Korvac was trying to get to Taa II, Galactus' warship to get a bigger power source.
Powers and Abilities
X-Gene: Halcyon has the mutant ability to stop his heart rate from ever going over 80 BPM, allowing him to be superhumanly cool under pressure.
Expertise: Halycon is an expert at any vehicle with an engine. This talent is enhanced by his mutant ability
Power Suit: Stark gave him a power suit that stimulates his adrenal system.