forte.exe

Anime
Bass originated from the remnants of PharaohMan's data, extracted by Wily to obtain his Ultimate Program. Initially without memories of his past life as PharaohMan, Bass learned about his origins and awakened his "true self" after abducting MegaMan and accessing his memories.

Seeking completeness, Bass attempted to consume Gospel's (Grave in the English anime) data, given their shared origin, but ended up being consumed instead. Following MegaMan's defeat of Gospel and restoration of devoured NetNavis, Bass took refuge in Shuryou Gospel's (Kid Grave in the English anime) android body, vowing revenge on the world. He later reappeared as the creator of Allegro in Axess and tried to absorb MegaMan and ProtoMan's Ultimate Programs at Stream's onset. However, he was easily defeated by Slur and imprisoned in the UnderNet, losing his means to traverse the human world.
In RockMan.EXE: Program of Light and Dark, exclusive to Japan, Dr. Regal captures Bass and brainwashes him to obtain the Tadashi Hikari Program. Upon regaining consciousness, Bass aimed to make Regal pay for using him as a pawn, even if it meant allying with MegaMan. Realizing they were no match for Nebula Grey, MegaMan allowed Bass to absorb his Ultimate Program. The resulting BassCross eliminated Nebula Grey, but Regal summoned a black hole in a desperate attempt to destroy both Navis. Bass saved MegaMan before getting sucked into the black hole himself, absorbing Nebula Grey’s power, which proved crucial in his rematch against Slur. After defeating her, Bass vanished, and his current whereabouts remain unknown.
Manga
In the manga, Bass debuted in Volume 3 when MegaMan and Protoman explored the UnderNet. Like his game counterpart, he once faced Serenade and aspired to wield similar power. Continually clashing with MegaMan, ProtoMan, and their operators, Bass was eventually taken by Dark MegaMan (Dark Rockman) and LaserMan, who sought to transform the world into the Dark Kingdom. Dark MegaMan failed to absorb all of Bass’ power, disconnecting from his soul. Drawn by Nebula Grey’s dark energy, Bass fought it, fusing with MegaMan to form BassCross MegaMan upon failure. After MegaMan used Beast Out to defeat Nebula Grey, Bass destroyed Dr. Regal's submarine. He resurfaced during the quest for the legendary program to defeat Gregar, saving MegaMan from Cyberbeast Falzar and absorbing Falzar to regain parity with MegaMan. As the Cyberbeast merged and began deleting the real world, Bass aided MegaMan, transferring all his power after encouragement from Serenade. Compared to the anime and games, Bass exhibits a deeper rivalry and friendship with MegaMan.