Trinity is the collective name of the Trent triplets, super-powered siblings seperated at birth.
When the three were first born, it was obvious that Violet and Pearl were mutants, while their brother seemed to be a normal human. However, it soon became apparent that Violet's massive power was out of control. Their parents were forced to bring Violet to Reed Richards and the Future Foundation, who determined the best course of action was to raise her in order to study her powers. And so Pearl and Jason were raised without Violet.
When the two were nine years old, Pearl enrolled at the Jean Grey School for Higher Learning. When Jason joined her to preview the campus, the school was brutally attacked by the Hellfire Club, folowing this brutal experience, Jason's powers manifested (He would later be revelaed to be an inhuman rather then a true mutant) . However, he was determined not to get involved in the mutant politics, preferring to abstain from joining his sister with the X-Men.
When Jason was 13, the Masters of Evil kidnapped him and some of his friends and held them for ransom. The Avengers managed to save them, but Jasn was forced to use his powers offensively to save his friends. he was convinced by the Vision and Scarlet Witch to enroll in the Avengers Academy.
Jason, now known as Conundrom, and Pearl, now known as Inferna, were soon enrolled in the Uncanny Avengers Youth Branch, a Gifted/Talented program to ensure unity between their schools. For the first time, They met their oldest sister Amethyst. While Conundrum welcomed her with welcome arms, Inferna took a bit to trust her.