Adam first appears in the first series episode "Dalek" as a young researcher under the employ of Henry van Statten, who is the owner of a museum of extraterrestrial artifacts in an underground bunker in Utah. Adam mentions that he is a genius, having successfully hacked into the United States Department of Defense computers when he was eight years old. He quickly forms a mutual attraction with the Doctor's companion Rose Tyler and informs her of his desire to see the stars. After a live Dalek manages to break free and slaughter its way through the base, Adam finds himself fleeing along with Rose. At the end of the episode Rose asks the Doctor to take Adam along with them in the TARDIS. The Doctor refuses, but Adam is forced to jump in the TARDIS when the museum is to be filled with cement.
In the following episode, "The Long Game", the Doctor, Rose, and Adam arrive on a space station in the year 200,000, and Adam is overwhelmed by culture shock. Tempted by the wealth of information and technology available to him, he has an advanced computer interface port installed in his head that allows him to access the future's computer system. The device itself activates by snapping your. In an attempt to change his fate in the past he tries to transmit information back to 21st century Earth using Rose's modified mobile phone. His attempt backfires and the villains running the station attempt to extract information on the Doctor directly from Adam's brain. As punishment of Adam's breach of trust, the Doctor returns him home, despite his pleading, and destroys his answering machine. When Adam's mother returns home, she reacts with shock and horror after inadvertently activating the implant installed in his forehead.
In the IDW Publishing comic book series Prisoners of Time that was released to celebrate the 50th Anniversary of the original Doctor Who, Adam is the main villain. After his mother dies he acquires a Vortex Manipulator and kidnaps all of the Doctor's previous companions. He is out for revenge because the Doctor erased the technology from the future that could have saved her. Adam initially teams up with The Master to help him capture and eliminate the Doctor's companions. He gives the Doctor the choice of saving one companion and that the rest must die. Unfortunately his plan is foiled when the Master betrays him giving all the past iterations of the Doctor time to arrive in their modified TARDIS that is homing in on the Eleventh Doctor's. Eventually the companions are freed and he is killed at the hands of the Master.
In the end, Adam realized that his desire for revenge didn't go as far as obliterating trillions of innocent beings. This gave him the motivation to fight back against the Master and earned him the respect of the Doctor.