Remembrance of Courage Past:
Courage's mysterious past comes to light when his parents were forcibly sent to space by a cruel veterinarian. When Muriel and Eustace notice he is not responding, still haunted by that traumatic event, they take him to the same vet that sent his parents into space, unaware that the vet is now going to send Courage off to space as well. When Muriel and Eustace discover this, the vet attempts to send them off along with him as well to keep them from interfering with his evil space research plans. Courage must save his owners after realizing that Muriel has become a major person in his life, besides his parents.
Perfect:
When Courage cannot do anything correctly, he is approached by the "teacher", who is the manifestation of Courage's own doubts and insecurities that have plagued him. She starts training him strictly into becoming a perfect dog, until Courage learns that even with his own flaws and imperfections, he can do anything and embraces that he is fine the way he is.