|Nano Item||Pony Puff Princess Doll|
|Voiced by||Kat Cressida|
Dee Dee is the older and caring, but totally ditzy, sister to Dexter and is the clumsy fool that caused the player to go too far into the future at the game's start. Even though she seems incredibly dim and not nearly as bright as her brother, she still loves Dexter. Her favorite doll is the Ponypuff Doll, her best friends' names are Mee Mee and Lee Lee, and she utterly despises Mandark, even though she knows that Mandark is in love with her. She has an imaginary friend called Koosalagoosagoop (Koosy for short) who lives in the land of Koos.
FusionFallIn FusionFall, Dee Dee is the one who caused the player to go too far into the Future at the game's start by pushing a button on Dexter's Time Machine. She has apparently inherited the house from her parents, who fled to Tech Square. Her Fusion is found within the Genius Grove infected zone, which is Mandark's old home. Due to her ditzy nature, she mistakes her Fusion for a ballerina monster. In The Future, even though she isn't found, she is in Dexter's house according to Dexbot Q-33.
Most of Dee Dee's missions involve taking out monsters around the Genius Grove area, but she has her parts in other characters' missions (such as one that involved one of the Kanker sisters). Despite the fact that Dee Dee knows she helped cause the problem with the player in the beginning, she never really talks about it if the player talks with her. She has two best friends who are nearly exact twins of her, Mee Mee and Lee Lee, and neither girl has been mentioned by Dee Dee or anyone else, hinting that Fuse might have gotten to them already. Dee Dee mentions she has an imaginary friend, Koosalagoosagoop, but it is never seen in the game.
In the "Delivery!" mission, Dee Dee is one of the NPCs to whom Chowder has the player deliver cakes. When Dee Dee receives the cake from the player, she mentions that she needs it for her ballet banquet.