Carmen Porter is Dean's fantasy girlfriend, who lives with him and works as a nurse at a local hospital.
In "What Is And What Should Never Be" Dean meets her in his apartment in the alternative world created by the Djinn. She is dating Dean and living with him. She also knows all of Dean's favorite foods and beer. She is Dean's ideal girlfriend. When Dean goes to celebrate his mother's birthday, Carmen tags along. When Dean finds out it is all a dream, she tries to convince him to stay.
In the real world, she is a model for Dean's favorite beer. Carmen is not real, but the model on the beer ad is.