Lawrence Trask was the son of Bolivar Trask, the original creator of the Sentinels. 'Larry' had always thought that his father was killed by the X-Men, believing that his father's fears had been realized and had fallen fowl to humanity's successors, when it was really the Sentinels that had betrayed humanity and not the mutants. He threw himself relentlessly into creating a more powerful, unbeatable guardian for humanity, and Dreadnoughts to seek revenge for the death of his father. Initially, He had the help of Judge Chalmers, but when Chalmers discovered the extremes his ward was willing to go to, and his true intentions, the judge made the hard decision to reveal the 'family secret'.
When the Sentinels discovered that he was a mutant, they put into action his last orders as their leader, "Secure ALL Mutants in area - and DESTROY them !".
Cyclops used the Sentinels' system of logic against them - sending them on a quest into the heart of the Sun, claiming that it was the source of mutation.