Theo is second ranked as one of the most unpopular in Westchester Country Day and one of Nikki's friends. He used to have a big crush on MacKenzie but has moved his interest onto Zoey Franklin. He is known for being the school nerd. In Dork Diaries: Tales From a Not-So-Talented Pop Star, it is revealed he plays jazz guitar expertly and is in the school orchestra and plays first Cello . Despite being described by Nikki as one of the smartest people in school, he hopes to one day go to Hogwarts and buy a wand.
Theo has brown curly hair with buck teeth. He is hinted to be Caucasian by the way he acts and talks.
All is known is that Theo's dad owns the Queasy Cheesy restaurants in Westchester and the francise all over the eastern part of the United States.