Treble is Bass' robot wolf, or lion depending on the source. Like Rush, Treble can assume a jet-like form (as seen in Mega Man 8) and fly.
After Bass stole designs for the Rush Adapter during the events of Mega Man 7, Treble has been able to transform into an armored suit for Bass, the "Treble Boost". This gives Bass limited flight capability and increased firepower.
- In Japan, Treble's name is Gospel, which was left untranslated in the Mega Man Battle Network series. This is also true of the anime, both in English and Japanese.
- Treble is one of the many characters who have music-inspired names.
- Despite the fact that Bass made a small cameo in Mega Man 9, Treble was nowhere to be found.
- In Mega Man Battle Network 6, the Cybeast Gregar appeared as part of the main plot and the final boss. Both of these characters' designs are based on Treble, but with a different color scheme.