Early life

Jack Hart was born in New Haven, Connecticut. He is the son of Philip Hart, a scientist who created an energy source called "zero fluid", and Marie, an alien humanoid woman of the Contraxian race. After being exposed to a vat of zero fluid, Jack underwent a mutagenic change and gained the ability to project concussive energy from his body. After gaining these powers, Jack began his mission of vengeance against the Corporation that killed his father. This led to Jack fighting other superheroes such as the Sons of the Tiger and the Hulk. He also fought the White Tiger.^[4] Eventually, he killed Stryke, his father's killer.^[5]

Later, Jack mistakenly fought Iron Man. Being new to super-heroics, he asked Iron Man to take him on as an apprentice, which he did, to show him the ropes. Jack teamed with Iron Man, Nick Fury, Guardsman, Jasper Sitwell, Jean DeWolff, and the Wraith, and battled Midas. Jack was briefly turned to a golden living statue by Midas, and then freed from this golden state by Iron Man and Yellowjacket.^[6] Jack then aided Iron Man in fighting the Soviet Super-Soldiers on the moon.^[7] Jack aided Iron Man against the Rigellian Commander Arcturus.^[8] Jack later went off on his own, and fought Hemlock.^[9]

Being a Hero

Later, Jack moved past his mission of blind vengeance and became a true hero, working with various other superheroes such as the Defenders. Jack fought the Thing, who was under mental control of the Machinesmith.^[10] Jack Hart was then reunited with a college girlfriend named Marcy Kane (who was also a fellow graduate student of Peter Parker, a.k.a. Spider-Man). Marcy, a scientist, and S.H.I.E.L.D. offered to help find a cure for Jack's dangerous super powers. Jack fought some S.H.I.E.L.D. agents, and his powers were temporarily dampened by Spider-Man.^[11] Marcy turned out to be a Contraxian agent sent to Earth to find Jack. It was at this time Jack learned of his half-Contraxian heritage. Marcy took Jack to Contraxia, where he discovered that his powers had become much stronger, and saved the home-world of his mother by reenergizing its dying sun. The Contraxians could not find a solution for Jack's unstable powers, and he left Contraxia to wander outer space in exile.^[12]

While wandering space he was captured by the Stranger. He later escaped captivity on the Stranger's planet.^[13] Jack fought Quasar during his return to Earth; however, Jack exploded when his containment suit was breached in battle with the Presence.^[14] Jack was retrieved from space, revived and mentally controlled by Moondragon, and he attacked Kismet.^[15] The damage to his armor led Jack to seek aid from the Silver Surfer, who found an alien armorer on Anvil who designed a new containment suit for Jack. Jack then battled Nebula and Geatar.^[16] Shortly after this adventure, Jack fell in love with the alien warrior woman known as Ganymede, though she did not return his feelings.

In an effort to save R-76, an outpost manned by the Rigellians, Jack of Hearts was injured in battle with the Servitors. Jack was rescued by a team of Avengers, and succeeded in convincing the Infinites to restore R-76.^[17] Subsequently, Jack and these Avengers were captured, first by the Shi'Ar, and then by the Ruul acting under the orders of the Supreme Intelligence.^[18] Jack and the Avengers eventually escaped to Earth and helped reverse a plan to have Earth consumed by Ego the Living Planet.^[19]

Jack's return to Earth happened during the period known as the Kang War, and Jack of Hearts was accepted as a member of the Avengers, becoming the fifty-second superhero to join the team, though the traditional welcoming ceremony for new Avengers were deferred given the nature of the crisis they faced.^[20] During his tenure, the Avengers teamed-up with the Justice League of America,^[21] and fought the Red Skull for unleashing a biological weapon at Mount Rushmore, killing many civilians.^[22]

Death

When his power levels began to increase beyond the capacity for his containment suit, Jack of Hearts chose to commit suicide rather than continue living in an isolated containment room for 14 hours a day. Jack took a child murderer who had abducted Cassandra Lang, the daughter of Scott Lang (the second Ant-Man), along with him when he exploded in space. With his uniform destroyed in the blast, the naked body of Jack of Hearts drifted deeper into space.^[23]

Avengers Disassembled

At the onset of the "Avengers Disassembled" event, Jack reappeared in uniform as what appeared to be a zombie just long enough to blow himself up, killing Scott Lang and destroying half of the Avengers Mansion.^[24] Jack's return was caused by the reality-shifting powers of the Scarlet Witch through methods that have remained ambiguous.^[25] Unlike his prior explosion in space, Jack's body was never recovered from the ruins.

Afterlife

During the adventures of Hercules in Hades, Jack can be seen playing slots to win a chance to return to the living. This is not the intended way the afterlife should operate, according to the characters. Jack wins, and excitedly declares that he is next for resurrection.^[26]

The Children's Crusade

Iron Lad (the young Kang the Conqueror) transports the Young Avengers and the amnesiac Wanda, no longer the Scarlet Witch, back to the onset of the "Avengers Disassembled" when Jack had been used as a weapon to destroy the Avengers. While there they discovered that he was actually the real Jack of Hearts, summoned by Scarlet Witch. Undead and quite miserable, Jack pleads with Wanda not to go through with her monstrous plan, unaware that he is facing a different Wanda. The pity of this and the horror of seeing Jack blow himself up, shocks Wanda into recovering her memory—and therefore her powers. As an unexpected side effect, the life of Scott Lang is also saved, as the Young Avengers take Scott back to the future with them when they depart, thus saving his life while preserving the timeline as everyone still 'saw' him 'die' in the explosion. Jack's last words before exploding were, "I'm sorry."^[27]

Marvel Zombies Supreme and resurrection

Jack Hart returned to life once more in the second issue of the Marvel Zombies Supreme mini-series. While defending scientists at Project Pegasus, (which has been besieged by zombiefied clones of the Squadron Supreme) a team of special operatives led by Jill Harper and the superhero known as Battlestar came across a source of zero-point energy which Harper believed could help them stop the zombies. The zero-point energy unexpectedly reformed itself into corporeal form as Jack, who returned to life wearing his original suit for unexplained reasons. Harper managed to revive Jack, who was temporarily amnesiac and fainting from the stress of becoming human again. Although initially weakened, Jack quickly regained control of his powers and assessed the situation. Using his powers, Jack destroyed the zombies and saved Harper's life after she became infected with the zombie virus. Afterwards, the two shared a romantic kiss.^[28]

Jack Hart was absent for some time, but eventually returned to a more public life when he literally crashed into the apartment of Jennifer Walters (She-Hulk),^[29] and found that he was now able to eat, drink, and sleep normally for the first time since his accident.^[30] As Jack regained his powers, he and Jen became romantically involved, Jack assisting Jen in the Reckoning War conflict as they aided the Fantastic Four.