In the beginning of the manga Dr. Berg works for the colony of MO-V. He is the creator of the G-UNIT mobile suits and their powerful special feature, the PX System. During the time period that Lady Une was convincing the Colonies to join OZ, Berg sends secret messages to OZ about the G-Units he created. After he defects to OZ Prize he continues to play both sides against the other by continually upgrading their Gundams. His goal is to develop the perfect weapon and will happily make whatever sacrifices necessary without any question of morality. His fail-safe, the "Auto-Destruct Program Berg-01" program that he activates with his dying breath, further proves his shallow nature. The intention of this program is to send Grand Chariot crashing into the Earth after destroying everything in its path - including the colonies starting with MO-V. His murderous plan is thwarted by Odin Bernett in the end when he destroys the OZ Prize flagship with a modified version of Gundam Griepe using parts from the other two G-UNITs.
During the final battle between the Bernett brothers and OZ Prize, Berg revealed to the brothers that he was the one responsible for the shuttle accident that killed their father. He claims he needed to kill Mr. Bernett so that MO-V would stop funding the the long-range engine project and instead fund the construction of Berg's G-Units.