Dark Heart was one of Grimlord's henchmen that bested all others and was relentless to destroy Ryan. The Troopers detected human DNA in Dark Heart and Ryan believed he was his father. Dark Heart invaded Ryan's dreams and he did believe Dark Heart was his father. After he lost to Ryan in a real battle, he ordered him to destroyed him but Ryan refused. Dark Heart was sent for termination by the other mutants. By running away, he is seriously damaged and Ryan brought him to the lab to discover he is indeed Ryan's father. Ryan gives his father his memories back but Dark Heart is determined to defeat Grimlord because he felt it is his responsibility. He fought alongside Ryan but is defeated in battle and taken to Grimlord. He is then rescued by Ryan and taken to a secret lab in the mountains to be repaired. Dark Heart and Ryan survive the lab being destroyed by Air Striker. Together, they infiltrate Grimlord's dungeon and fall into a trap. They managed to escape but was severely hurt by one of Grimlord's goons. He became human again but was taken away from Ryan by Grimlord again.