(I offer this information to give folk an idea of how the Xmen first formed in the comics. The
XMen team formed in comics in 1975.)
Russian authorities had watched Colossus from a young age, with the hope of creating their own XMen/Avengers team. One day a tractor’s brakes failed, sending the huge iron machine hurtling towards Piotr’s younger sister, Illyana(who would later be the New Mutant, Magyck). Piotr hugged his sister and transformed into his steel form, destroying the tractor.
Charles Xavier discovered Piotr Rasputin’s mutation and made plans to contact Piotr.
Xavier mind-controlled the government spy who was assigned to watch Piotr, and set up a meeting between Xavier and Piotr.
Xavier offered to help Piotr train in the use of his power, and asking Piotr to help Xavier recruit and train mutants so that these mutants would not be dangers to society.