sentences:  Mr Smith appeared to start to self-destruct in "Prisoner of the Judoon" when ordered to do so by Sarah Jane while she was under the control of an alien entity, but Luke was able to override the self-destruct by pointing out the conflict with that order and Mr Smith's prime directive to protect humanity, given that the resulting explosion would destroy several city blocks.He demonstrated displeasure and sarcasm in "The Mad Woman in the Attic" when told that K9 would return to residing with the Smith family.Mr Smith was initially openly resentful of K9, a feeling which was mutual.