First appearing in Mega Man 7, Bass observed Mega Man as he struggled to thwart Dr. Wily's escape from prison. When they first met, Bass did not introduce himself as one of Wily's Robot Masters but neither did he proclaim himself to be Mega Man's enemy.
He continued to observe the Blue Bomber's activities until he was ordered by Dr. Wily to infiltrate Dr. Light's lab and steal the plans for the Super Adapter technology Light had designed for Mega Man and Rush. Since then, Bass has made it clear that he and Mega Man are fated enemies and is determined to prove to Dr. Wily, Dr. Light and the world that he is the most powerful robot that ever existed.
Bass has often rebelled against Dr. Wily and gone after Mega Man on his own, but Mega Man does not regard Bass as an enemy and is hesitant to fight him. Numerous times, Mega Man has tried to convince Bass that he doesn't need to prove his superiority and that there must be another reason for his being. Bass has yet to be swayed by Mega Man's reasoning and continues to fight out of pride, often ignoring Dr. Wily's commands and only helping the doctor when he feels it suits him.
Despite being convinced that he is more powerful than Mega Man, Bass has never defeated him and their battles have always ended either in Mega Man's victory or in a stalemate.
Bass possesses all the same powers and abilities as Mega Man, though some of these abilities have been modified to give him an advantage. His Bass Buster can fire straight beams of plasma or rapid-fire pulses like a machine-gun. His body armour provides extra resistance to attacks and his boots release bursts of air that allow him to double-jump accelerate into a dash, unlike Mega Man who slides feet first. The shape of Bass' helmet prevents him from sliding through narrow spaces like Mega Man can, though. He can copy the abilities of other Robot Masters just like Mega Man and even has a Super Adapter that allows him to merge with his lupine partner, Treble.