Excitable and fun loving, Carlos loves anything having to do with fun and enjoys very childish activities (such as going down a swirly slide). He is the youngest, shortest, and most immature of the group. He is shown to be optimistic, childish, energetic, impulsive, unpredictable, and reckless. Because of his childish nature, he almost always tends to rebound quickly from setbacks, with his sudden break up in Big Time Single being a rare exception.
He is also very superstitious, believing in ghosts and the paranormal, as well as being cautious of bringers of bad luck like black cats and broken mirrors. He is easygoing and very persuadable, which often gets him into trouble. He can get really sensitive, he is extremely prone to accidents (possible reason for the helmet), he acts impulsively and therefore casually says whatever he has on mind no matter what. Moreover, he is always the last to figure out what is going on or what the guys plan.
Carlos usually suggests thinking "happy thoughts about kittens" when his bandmates get into arguments. He sometimes has little disputes with Logan, while he constantly get in fights with James. A running gag is that Carlos usually almost gets the guys caught or in trouble, and he says the wrong things at the wrong time and is the least sophisticated non down to earth guy in BTR. It also says that he is nicknamed "The Wild Rush".
Carlos is the youngest member of the band and has been shown to be very illogical, believing in ghosts and the paranormal as well as being cautious of bringers of bad luck (walking under ladders, black cats and broken mirrors.) Carlos has never had a real girlfriend except Mercedes Griffin who forced him. His love interests include the Simms Twins, The Jennifer's, and Stephanie King, but he likes almost every girl that comes to the Palm Woods . Carlos seems to be very easy going, and whenever the others start to get into a fight, he suggests thinking "happy thoughts about kittens". He sometimes gets into little stupid fights with one of his bandmates, Logan Mitchell, as shown in "Big Time Photo Shoot". It has become a running gag where Carlos almost gets the guys caught or in trouble in which the gang bumps him in the ribs to shut him up.
He's never had a real girlfriend before, though in "Big Time Dance," he does asks the Jennifer's to the End of the Year Dance, but ends up with Stephanie King. In the episode Big Time Fever, everyone but Kendall succumbs to the Hollywood Fever, and Carlos is turned into a Jennifer after the Jennifer's make him believe the only way to make it big in this town is to step on everyone under him and feel he is better than everyone else. In the episode "Big Time Sparks" Gustavo accuses the boys of being bad luck, when they see this, Logan and Carlos become the "Good Luck Patrol" to protect Jordin Sparks in the episode "Big Time Sparks", but, because they are bad luck, they knock her down a well, and after numerous fails, leading all of the boys except for Carlos to also fall down the well, he jumps down the well, because he was lonely. Carlos is also known for being the happiest of the bandmates.
In the new season Gustavo sets him up with an actress to be his first girlfriend so he can experience heartbreak for a song, but remains happy and accepting during their time together. Gustavo did come clean and the actress decide to make their relationship a reality, but she admits she hates corn dogs. Carlos then breaks it off, because he loves corn dogs. It is rumored that his love interest could be Stephanie King in "Big Time Dance" (it has been shown to us that she could be interested in him and he could like her) In which he is seen getting pretty close to her and calls her "hot" but its still a mystery cause in later episodes Stephanie no longer appears in episodes and Carlos claims he still needs a girlfriend in "Big Time Concert."
- Carlos will meet Winnie the Pooh and his friends in Winnie the Pooh meets Big Time Rush (Full Movie).