Theo is a confident, bossy and straight laced conservative who always want to be in charge. Theo takes what he does very seriously and is a very skillful fighter. Master Mao saw his potential along with his excellent fighting skills, and chose him to be a new guardian of Dai Shi. But now that Dai Shi has been released, Theo was selected to become the Blue Ranger. Theo's weapon of choice is the deadly tonfa, which he mastered in his second year of training. RJ had Theo show Casey how to master the Numchucks. He has been friends with Lily for years and became jealous when her friendship with Casey started budding. Unbeknownst to even Lily, he has a twin brother. Even though it is clear to Fran and RJ that Theo's feelings extends behind what meets the eye, Theo denies his feelings go beyond friendship. Theo is learning he can't always be in complete control and one time he lost his confidence for loosing a battle to one of the Five Fingers but RJ helped him out and was able to regain his confidence just in time. Theo is such a great multi-tasker that he took it for granted to the point that the quality of his work was failing. he was unable to see this, as he didn't know anything beyond doing many tasks at once. He reveal that as a child, he was always expected to excel in everything. Master Swoop taught him to concentrate at the task at hand and to be balanced. He is given the Jungle Fans to defeat some high-flying servants of Carnisoar and destroys them with the Bat animal spirit zord.

When Dai Shi beat up the Rangers profusely in a big showdown and sequestered R.J., the Rangers were left Master-less. R.J. told them they knew what to do, which was to go back to basics, which led them back to the Pai Zhuq Academy room where Dai Shi was kept. The Rangers noticed the masters' animal spirits etched in the wall and wondered where the gorilla, penguin, and antelope masters. They were greeted once more by their fallen teacher Master Mao. He sent them to the Spirit World to be trained by three fallen masters. They put them through tests, Master Lope sent Theo to a dimension where he had to surpass his ego and embarrassment in singing karaoke in front of a large audience. After complaining and then realizing what he had to do, he had passed the test and granted the Claw Boosters, Jungle Master mode, and Antelope animal spirit zord.

Theo later could summon the Bat Spirit Ranger when needed. When Lewin came to town, he realized he was jealous of his lazy but talented brother. Lewin was mistaken for Theo and captured by one of the Phantom Beast Generals. Theo saved his brother and he discovered his true identity and their bond became stronger. Theo was discouraged in revealing his true feelings to Lily when she told him they were only friends but Fran clarified he never really asked her on a date. After the final battle, he finally asked her on a date and she accepted.