When Carl Met George

George and the Missing Puzzle Piece (also known as When Carl Met George)  is the first half of the 6th episode of Season 13. It first aired on April 5, 2010 with D.W. Swims with the Fishes.

Synopis
In this episode, George tells the story of how he met his friend Carl, who has Asperger's Syndrome. At first, George didn't know about Carl's disorder, and George thought Carl acted a bit strange around him, but he wasn't sure why. Later, when George goes to visit him again and brings his dummy Wally, Carl is unexpectedly terrified of it and it is then revealed by Carl's mother that he has Asperger's Syndrome. George later goes to The Brain for advice on what Asperger's Syndrome is, and The Brain tells him all about it. George then understands what Carl is going through, and decides to bring him a book on trains(Carl loves trains) and also gives him the puzzle piece that accidentally fell into his bag the first time they met. The last scene is George in his bedroom, with Carl sitting at his table(just like he was at the beginning of the episode) still going on about his train picture, but then he almost immediately comes back and says to the viewers "It was nice meeting you" and George explains how he taught Carl to say that, and how Carl taught George to understand his behavior.

Triva
This episode is Carl's debut. He would appear again in the episode Buster Spaces Out.

The Brain is the only other main character besides George to pysically appear in this episode. Arthur and Francine do appear, but this was The Brain explaining Asperger's Syndrome to George. The episode has mostly minor characters in it though in the background.