A BehaviorChip programmed to your own specification. While it has many of the flaws and drawbacks of a regular Behavior Chip, it also has obvious benefits when you are targeted by mental attacks.
If you are ever about to make something that is contrary to your normal objectives or personality, the chip cuts in and prevents the action. Thus, you won't attack your friends, reveal your secrets or otherwise cause a Stunts: Setback to your regular agenda. This is especially important if you are mind controlled, dominated or possessed.
As a game effect, this prevents Stunts: Setback results from social interaction and mind control. You still suffer the full regular effect of the interaction.
The Buddy Chip can be a two-edged sword. The chip cab be bypassed if an an attempt at mind control or interaction accidentally hits upon an action the Buddy Chip is not set to interveine against - strictly a roleplaying descision. Someone with access to your Buddy Chip software can use its programming to advantage, effectivelly bypassing your willpower. In this case, any successful interaction or mind control gives a Setback result. Someone who can reprogram the Buddy Chip can turn it into a BehaviorChip.