Leonardo is the most serious, mature and focused of the team. Being the designated leader of the group, Leonardo is very enthusiastic about his role. He is also a big science-fiction fan (or "nerd" as referred to by his brother Raphael). His favorite series is Space Heroes, while his favorite character from the show is Captain Ryan. Leonardo has a habit of memorizing Captain Ryan's best lines from the show and sometimes repeating them during battle. Leonardo is so caught up with Space Heroes that he relies on Ryan's character traits more than on his own intuition, which often causes his brothers (especially Raphael) to question his leadership.