X-Men Origins: Colossus #1

Synopsis

When young Piotr Rasputin learns of his brother's death, it triggers his mutant power and his skin becomes organic steel. As the years pass and Piotr tries to live a normal rustic life with his parents and sister, Mikhail's friend Alexander, who witnessed the stunning transformation, researches the mutant condition and his inquiries bring him into contact with Charles Xavier. The Russian government also learns of Piotr's amazing powers but before they can make a move, Professor X intervenes and invites the young mutant to join his all new X-Men.