Gary was a failed prototype for the Carebot 6000.  He was supposed to be a conscientious and helpful cybernetic assistant.  However, due to a design oversight he was programed with too much caring, but not enough memory.  As a result he feels deeply about everything, but inevitably forgets something he was supposed to take care of.  In this case, he forgot to water the flowers.  It is a never ending cycle for this tragic robot.  While he is overwhelmed by the demise of the flowers he will forget to feed the goldfish.