The past of Jonathan Hart of Earth-9997 mirrors that of his Earth-616 counterpart. In recent history Jack of Hearts would become a slave to the Skull through circumstances that have yet to be revealed. Following the defeat of the Skull, Jack of Hearts would become a knight under the command of King Britain in the UK.
There he would be one of the many soldiers who would defend Buckingham Palace from attackers, notably the Tong of Creel who attacked the castle to retrieve a portion of "Crusher" Creel which was under the King's protection. Jack of Hearts would become the object of affection of Luna of the Inhumans. However it has not been revealed if they have established a romance.
Jonathan also briefly aided other heroes in helping Mar-Vell in collecting items of power in his quest to kill Death by collecting items of power on Earth. He also attended the wedding of King Britain and Medusa and helped fight off the Deviants during their attack on the castle, secretly led by Mephisto who was disguised as the Grey Gargoyle. His current whereabouts are unknown.