BAJAR stands for brain-in-a-jar. He is a well-informed scientist and possible companion. Though he is sometimes hard to control because of his slightly odd actions due to spending so many years without a body to control.
BAJAR can not do anything combat wise unless he is put in a robobrain body. Although his jar can be carried around and he can be asked questions for information. He is not willing to join the party unless the Prisoner has some scientific background. He won't join if the minds of the think tank have been erased, even to save ZAX.