Styles was a somewhat arrogant man, coming off with an attitude of superiority. He took extreme pride in his assignment as master of the Excelsior, which had been outfitted with an experimental transwarp drive. The night before the Excelsior was to be launched from spacedock, Styles encountered Montgomery Scott , his newly-assigned captain of engineering, telling him that he was "looking forward to breaking some of the Enterprise's speed records."
That same evening, Styles was informed that Admiral James Kirk was attempting to steal the Enterprise, and immediately mobilized the Excelsior crew to stop him. Upon the Enterprise's emergence from the spacedock, Styles contacted Kirk, reminding him that, if he followed through with the illegal action, his career in Starfleet would be over. Kirk ignored him, however, and took the Enterprise to warp. Styles expected to quickly catch up to the Enterprise utilizing the Excelsior's transwarp system, but was unpleasantly surprised to find that Scott, who was Kirk's former chief engineer, had sabotaged the transwarp drive.
By 2290, Styles had been replaced as commanding officer of the Excelsior by Hikaru Sulu.