Batella was a robot under the command of the Klathi and was also programmed to obey the orders of a Joebb called Caval, the Klathi's ally. He was assigned the task of protecting the Klathi's crashed ship that was hidden in the docks and attacked the Seventh Doctor and Nathaniel Derridge when they tried to enter it, only to be temporarily blinded by the Doctor.
When Caval turned against the Klathi due to their evil schemes, Caval instructed Batella to act against the Klathi too. At the same time, the Klathi instructed Batella to kill Caval, the Doctor and all the other opposing threats, who Batella was originally programmed to protect. Confused with so many instructions, Batella self-destructed, taking the Klathi and their ship with it and saving London. (COMIC: Claws of the Klathi)