Dexter's Assistant is the third part of episode 2 in season one of Dexter's Laboratory. In this episode, Dexter turns Dee Dee into his assistant in order to win a science fair. However, Dee Dee proves to be much more intelligent than her little brother.
Dexter is in his laboratory working on a transportation machine. He turns it on and the countdown begins. Then, Dexter realizes that he has not pushed the button that will make this successful. The button is all the way at the bottom of the lab and he runs down there to quickly press it but he is too late and the power goes out.
The power turns back on and Dee Dee is there. Dee Dee says that she can help him with pressing the button. Dexter laughs in disbelief at this but he makes her do it anyway just to get a good laugh. Dee Dee tries to press the button but she keeps missing. Then Dexter tells her to get out of his laboratory. Dexter thinks that he needs to get a lab assistant.
Dexter goes into a closet where he has a bunch of brains. He takes a brain and goes to see what to put it in. He goes up to a rat and says no because it's too small, he goes to a giant robot and says no because it is too big, then Dee Dee is there. Dexter has no other choice. He must do it to her.
Dexter puts the brain inside of Dee Dee and she becomes smart. Dexter takes Dee Dee over the the transportation machine again and he gets in. Dee Dee tells Dexter she doesn't think this will work but he ignores her warning, starts the machine and tells her to push the button which she does. However the machine messes up and blows Dexter off from the top and shutting the power down again. Dee Dee says Dexter his "calculations were wrong" but she would take him to the problem before commanding his computer to turn the lights back on which makes Dexter mad saying nobody commands his computer but him.
Later, Dexter is going to combine chemicals. He must only do one drop and he is being very careful about it. Dee Dee comes up to him and starts pressuring him. Dexter yells at her to be quiet and he pours too much in and the experiment explodes and hid hair catches on fire. Then, Dee Dee puts it out with a bucket of water and gives him a hair growth potion.
Later, Dexter is working with fuses and he has a bunch of long flowing hair. Dee Dee tells him what fuses are right and what fuses are wrong but Dexter tells her that he knows what he is doing. Dexter cuts the wrong wire and it explodes in his face. Dee Dee tells him that they were all wrong. Then Dexter yells at her to get out of his laboratory and that he doesn't need her help so Dee Dee leaves and says that she doesn't need to help him either. Then she gives him a toy monkey and says that he can use that as an assistant.
Later, Dexter is at the science fair and shows his great invention. The winner of the science fair gets announced and the winner is said to be Dee Dee who has built a Merry-Go-Round machine. Dexter is angry about that and yells at his monkey toy for it. The toy monkey smashes its symbols on his nose and the episode ends.