Real Name: (?) NeramaniX-Treme came to Earth as an amnesiac, and was found by industrialist Martin Henry Strong, who called him Adam X and gave him his code name. Strong's agenda was to eliminate the X-Factor that makes mutations, a move Adam seemed to support because the one thing he remembered was that if not stopped, he would be responsible for killing every mutant on the planet. (Whether this is true or was told to him by Strong is unknown. This statement has never been followed up.) In return for information about his past, Adam agreed to work for Strong as a mutant tracker, a skill he put to use when tracking down Michelle Balters (Neurotap), the girl who had become his girlfriend. During that mission X-Treme met X-Force and fought them off. Later, X-Force tracked Adam down and convinced him that Strong was wrong and that he should work with them to stop him. Adam betrayed Strong and helped X-Force destroy his main facility, but then went his own way, not ready to join up with his new friends.
Some time later, X-Treme was captured by Arcade and forced to fight Shatterstar. Eventually the two fighters turned on Arcade and broke out of Murderworld. (It is important to note that Adam's participation in this conflict was set up by Sinister, who appears to have taken an interest in the young man.) X-Treme did come away with some of the information he was promised for fighting Shatterstar, which led him to Alaska.
While there, he happened upon the wreckage of Philip Summers's plane. Adam built a fire and performed first aid on Cyclops's grandfather, and kept him alive long enough to make it to a hospital. When Jean Grey-Summers came to visit, she sensed Adam's presence and met him for the first time. Using her telepathy, she then allowed Adam to give Philip a memory of flying a starship, which made the old man very happy. Then Adam left and was captured by Davan Shakari (Eric the Red), who brainwashed him into fighting Genis-Vell (Captain Marvel III/Photon II). After breaking the conditioning, Adam teamed up with Genis to defeat Shakari, who informed him of his heritage and his place as the rightful ruler of the Shi'ar. So far, X-Treme appears not to have returned home to pursue his claim.
Given his blond hair, the connection to Sinister (who once mentioned a third Summers brother), the fact that he felt a connection to Philip Summers, and the feeling Phoenix got about her family getting closer after meeting X-Treme, it appeared highly likely that "Adam X" is actually the son of Katherine Anne Summers by the Emperor D'ken, whom it is known kept Corsair's wife as a harem girl before killing her. However, according to secrets recently revealed by Professor X (as told to him by Corsair), this connection is impossible, since Kate Summers was pregnant when she was abducted and the child ripped from her dead body by D'Ken ended up becoming "Gabriel" Summers (Vulcan).