Dee Dee

Dee Dee is the deuteragonist of Dexter's Laboratory. She is Dexter's extremely ditzy, simple-minded yet cute and pretty big sister.

Personality
Despite her cuteness and beauty, she usually, in one way or another, sabotages Dexter's experiments and destroys the lab in every episode of the show (one episode even hints that she may be doing so on purpose), even though she seems to show care or love for her brother. Dee Dee also loves ballet, puppies, unicorns, messing around in Dexter's laboratory, and generally depicts all the stereotypes concerning normal girl activities.

Dexter
He is Dee Dee's younger brother who is a true genius. The only reason why she always interferes with his work and always entering his lab is because she loves to spend time with him and because she thinks his lab is a cool place to play and have fun. Like any other normal siblings do, the two will sometimes quarrel and even rival each other over some certain things to see who is best, especially at games and sports. Nevertheless, Dee Dee does deeply care about her brother and his well being.

Parents
Dee Dee seems to have good equal terms with her parents and hardly has any arguments with them. She even inherited her father's hair color and his playful personality. She also inherited her mother's crafty sportsmanship, especially in snowball fighting.

Mandark
Mandark, Dexter's rival and villainous counterpart, has a super crush on Dee Dee and wishes to make her his girlfriend. However, Dee Dee is not even aware of his feelings or she does, but she does not show any feelings for him.