He first appears as one of the two tritagonists of Descendants, its prequel novel Isle of The Lost, its spinoff animated series Descendants: Wicked World, its midquel Return to The Isle of The Lost, as well as Descendants 2. He also appears as a major character in both Descendants 3 and its prequel novel Escape From The Isle of The Lost.
Carlos was invited by Prince Ben (like the other Villain Kids) to Auradon to participate in their parents' plot to steal Fairy Godmother wand. He also has a fear of dogs because of what his mother had said to him about them, but Ben showed him that dogs are not that bad after introducing him to Dude. He later shows an affection toward the dog that will later blossom into a friendship. He's also a member of the Tourney team like his best friend Jay. Like everyone in his group, he chose good over bad and he seems to be be really interested in Jane the daughter of Fairy Godmother.
In the show he appears as more of a background character in the first series but a major character in the second season where he encounters Zevon along with Freddie, Jay and Jane and is trapped inside of a lamp by the latter and CJ Hook. He assists in defeating Zevon by attacking his puppet army.
In the sequel, Carlos is constantly attempting to ask Jane out on a date but is too nervous to approach her with the question. He along with Jay, Evie and Ben travel to the Isle once again to try and convince Mal to return however she continuously refuses only agreeing when Ben is kidnapped by Uma.
After freeing Ben and returning home Carlos finally brings himself to ask Jane to be his date to the upcoming dance which she happily agrees to.
At the dance Carlos as well as everyone else is horrified to see Ben dancing with Uma and proclaiming her love for her despite everything she had done to him. Carlos then says that he regrets risking his life for him now.
After Ben was revealed to be under the influence of a spell Carlos and the others watch on as he convinces Mal and Uma to stop fighting resulting in Uma fleeing. He appears once again during the final dance number celebrating with the other students.
In this third film in the Descendants series, Carlos helps the VKs to combat the newly evil Audrey. Along with Mal, Evie, Jay, Uma, Harry, Gil and others, he helps retrieve Hades's ember. He is separated with Dude and Jane for a while but they are reunited. Harry calls Jane 'ravishing', but Carlos quickly lets him know that she is also taken. However Carlos gets turned to stone along with nearly everyone else whilst Mal and Uma fight Audrey. After Audrey is defeated, Carlos is returned to his normal self and is seen again in the final dance where the citizens of the Isle of the Lost are set free.
- He is apparently a victim of child abuse from his mother according to the novel "Isle of The Lost" which can be backed up by the fact that he has the worst relationship with his parent out of all of the VKs and is even terrified of his mother. The first film displays this by having his mother treat him like a slave., and showing even less compassion than the rest of the parents.