He later serves a brief stint as an ally and apprentice of Iron Man, becoming a regular cast member of the series during Mantlo's tenure as writer. His debut appearance in a color comic book was in The Incredible Hulk vol. He was presented as an antagonist for the superhero White Tiger but his origin story in the following issue established him as a hero.

Jack of Hearts first appeared in the black & white magazine The Deadly Hands of Kung Fu #22 (March 1976), and was created by writer Bill Mantlo and illustrator Keith Giffen. The Zombies were later defeated with the help of Jack of Hearts. The character was resurrected as part of one of the Marvel Zombies mini-series where Zero Energy reforms into Jack of Hearts, bringing the character back to life. The return of Jack of Hearts and the explosion that killed Scott Lang was the launching point of the 2004-05 ' Avengers Disassembled'.

When his powers became uncontrollable he chose to leave Earth, exploding in space without harming any innocent bystanders. The lack of control became a recurring theme with Jack of Hearts, including his stint in the Avengers where he had to spend 14 hours a day in a containment room to prevent self-destruction. In an attempt to control his powers, Jack of Hearts built a containment suit that resembled the Jack of Hearts playing card. As a young man Jack was doused in Zero Fluid and gained super powers but was not in total control of his powers. Jack of Hearts, real name Jack Hart, is the son of scientist Philip Hart (creator of 'Zero Fluid') and an alien woman from the Contraxian race. He starred in his own four-issue mini series and has been a regular character in the Iron Man comics as well as at one point being a regular in The Avengers comic book. The character first appeared in The Deadly Hands of Kung Fu #22 (March 1976), and was created by writer Bill Mantlo and artist Keith Giffen. Jack of Hearts ( Jack Hart) is a fictional superhero appearing in American comic books published by Marvel Comics. Increased intelligence, strength, durability, and memory The Deadly Hands of Kung Fu #22 (March 1976)

Jack of Hearts by Kat Baxter