X-Men #12 (1965)

Continued from last issue... Cerebro is calling out an intruder alert prompting the X-Men to don their uniforms and come to the Professor's study to learn who this mysterious intruder is. Telling his charges that whoever is approaching the mansion is extremely powerful, he sends the group out to set up defenses including an ice wall, live-wire lined trench and fence posts rigged with grenades. When the X-Men return to the Professor, they are shocked to learn that their attacker is none other than Xavier's own brother. The Professor tells his X-Men that his father was a nuclear research scientist who was accidentally killed during a nuclear bomb test in the New Mexico desert. During his father's funeral, Kurt Marko, a fellow scientist, would come to comfort Xavier's mother. However, the young Charles knew of his less than noble intentions to take his mother and his father's wealth, position, and property; three things that Marko had become envious of. Shortly thereafter, Kurt moved into the Xavier mansion and married Charles’s mother. Kurt became a ruthless and verbally abusive step-parent and shunned his new family for his work. During this time Kurt's true motives would come out. One day, Kurt was thrown into a fury when his own son from a previous marriage, Cain, came to the Xavier Mansion after yet another expulsion from school. Cain turned out to be a cruel tormentor to young Charles. The Professor's narrative is interrupted when Cain's advancement on the mansion progresses, easily smashing through the ice wall put up by Iceman, much to the X-Men's surprise. Charles continues the story of his youth: He would explain that one day he overheard Kurt and Cain arguing over money. When told that he would not receive a handout, Cain suggested that Kurt had orchestrated the death of Charles's father (an accusation that Kurt would flatly deny). Charles entered and confronted them about the statement. During the moment of tension, Cain tried to throw chemicals at Charles; however Kurt attempted to stop them sending the volatile brew crashing to the floor causing an explosion and fire. Kurt carried the two boys out of the blast. Having been mortally wounded in the blast, he begged Charles to believe that his father's death was only an accident before dying. Cain has reached the second barrier, the electro-magnetic force field and live wire. As he is impeded by this barrier, Charles finishes the next part of his story. He explains that by his adulthood he found that his mental powers (which by this point have rendered him bald) could allow him to have an advantage over other students academically and in sports, however he decides against using it for personal gain. His trophy winnings earned the ire of Cain who pushed Charles too far one day and the two got into a fight. Charles won the fight due to his mental ability to read his mind and know his movements. Some days later, Cain attempted to make Charles cry out in fear by driving recklessly. He only succeeded in making the car drive out of control and smash through a detour sign and down a cliff. Cain bailed out, but Charles wasn't so lucky, however Charles would tell his X-Men that he was able to erect a mental shield around himself to protect him from the crash. Outside the mansion, Cain finishes with the live wire and breaks through the force barrier. He then makes it to the grenade traps and gas traps that were set out for him. He staggers through the gas traps and Iceman puts an ice barrier over the busted window of Xavier's study so no gas comes in. This allows the Professor to tell the final part of his story. Cain and Charles had grown and were enlisted in the military and had been sent to fight in the Korean War. Cain deserted while under fire and sought refuge in a cave. Charles rushed after him and they had stumbled into the long lost temple of Cyttorak. The greedy Cain grabbed a crimson gem that was left before an altar. Upon contact and reading an inscription, the gem transformed Cain into a hulking form. The cave began to collapse because it was being bombed from the outside. Charles escaped the cave in while Cain was buried under tons of rock. Finishing his story, Charles realizes that Cain had finally dug himself out from the cave and sought out his brother for revenge. With the last of the outer defenses, the X-Men sealed the mansion’s front door with a near impervious steel plate and waited for Cain's next move. Much to the X-Men's surprise, Cain is able to smash through the supposedly indestructible steel door and easily knocks the X-Men aside. Revealing himself for the first time in years, Charles looks at his brother -- garbed in a special mystical armor -- and calls him a human Juggernaut. This story is continued next issue...