Cecilia

Cecilia (nicnamed Cissy) is a character who appears in The Mystery of the Missing Dinosaur.

Appearance
Cissy looks like a female version of TD, with long, curly blonde hair and a pink t-shirt with a strawberry on it, similar to TD's tomato shirt. She also wears a blue skirt, pink socks, and pink flats.

In The Mystery of the Missing Dinosaur
In The Mystery of the Missing Dinosaur, Cissy was walking home from her Spanish lessons when she happened to stumble across TD's toy dinosaur, which had coincidentally flew in her direction. Cissy wanted to know where the dinosaur had come from, so she contacts the weather bureau for the wind direction that day. From that information, she determines the location the dinosaur had flew from: TD's house.

Cissy assumed that whoever owned the dinosaur had a great interest in science and was a genius. She then devised a cunning and clever mystery for TD to solve, leading him to Cissy's house. When TD solves the mystery and gets to Cissy's house, he gets his dinosaur back. As Cissy tells him about her mystery, TD realizes that he has met a mind equal to his own. At the end of the episode, when TD tells Cissy he'd be happy to help Cissy with a mystery, she responds, "Thank you, but I work alone."