Out of all the VKs, he arguably has one of the worst relationships with his villain parent. This is shown by the fact that she was not above using him like a servant and was even considered less important to her than her furs, something Carlos is aware of but doesn't like to talk about. She also instilled a deep fear of dogs within Carlos, but when Carlos was given the choice of going to Auradon Prep and having to deal with dogs (which he thought were rabid animals ready to attack) and dealing with his mother, he was more than willing to leave causing his mother to call him ingrate as he rushed to the car to get away from her. He seems to fear his parent more than the other VK (even more than Mal, who is afraid of her mother but more so of her disappointment) and was the last to choose good because of his fear of what his mother would do to her. Despite this he was able to fight back against his mother, as shown when she wanted to use the mascot dog dude as a new ear muffs he fought back and refused, even calling her furs stuffed. He did also ultimately choose good and move away from his mother's influence.
She held an initial fear of VKs. After the Family Day incident she wasn't above ridiculing the VKs out loud but mostly Mal. During the end of the film, she accepts the VKs and even dances with Carlos. It is revealed in Return to the Isle of Lost that she and Carlos began dating. There is more information about the couple in Descendants 2.
Jay is Carlos's best friend. The two are usually seen hanging around each other and interacting positively though they tend to get into fights throughout the film due to Jay's aggressive dominating thieving personality. The two fought with each other over eating candy in the limo and then Jay tried stealing a thing Carlos wanted. The two both enjoyed playing video games. The two also joined the Tourney team though Jay was far more successful due to the skills he acquired from thieving. However, after being taught by the coach that being a team meant working with each other, Jay insisted Carlos be included in the game and the two won.
Mal is the leader of the reformed VKs so he often followed her lead. She often had to remind him to focus like when he was playing video games. Despite this the two are shown to be close friends as she cheered for him when he won the Tourney tournament with Jay. She also managed to convince Carlos to join the good side as she understood him well enough to know he enjoyed being with Dude the mascot dog and being at Auradon.
In Wicked World, she was annoyed when Carlos took a while to turn everyone back from dogs to people but was concerned when he and Jay didn't come to pick her and the others up to the Neon Lights Ball and glad to know he was alright. He in turn was annoyed to find out CJ was framing her and carpet jacked him and Jay. Overall, she seems to act like an older sister to him.
While the two had less interaction, they were shown to be close. In the past, Evie was Carlos's first friend and even gave him his first pillow. The two were shown getting along as she cheered for him during the Tourney tournament and he helped defend her against Chad. While the two did not have much interaction during the film, the two were shown to get along. She cheered for him during the Tourney tournament and it is revealed in the past that Evie was Carlos's first friend and the two had crushes on each other in the past though it remains to be known what happened to those feelings (though since the two are in relationships with AKs by Return to Isle of Lost it is possible they see each other in a platonic light now).
While the two don't interact much, the two were shown to get along well in the film. Ben tried to socialize and be friends with all the VKs and he helped Carlos get ready for the Tourney tournament and getting accustomed to dogs through the mascot dog Dude. The two are shown to interact positively in Wicked World episode 10 where he let Jay hit Carlos for not helping them when they were turned into dogs until Mal pressured him to help.
While the two didn't interact much, she held a low opinion of the VKs. By Wicked World though, she has the least problem with him and Jay, but she finds his choice of Tuxedo to be ridiculous.
She didn't interact much with him though she saw him, Jay, Mal and Evie bake cookies and asked if his parents did since she thought the VKs' parents loved them, he didn't answer. Lonnie apologized for being insensitive.
He had no interaction with him but it can be implied they got along due to their association with Evie.
He doesn't have a high opinion of Carlos, as he dislikes the VKs. They didn't have a smooth friendship as of the events of Family Day.
The two didn't interact much but it is presumed they are friends especially since the two are VKs.
The two had little interaction, but she was shown to be distrusting of VKs and annoyed when he and Jay didn't come to pick her and the others up (not knowing he was carpet jacked). She also admitted to not worrying about him when he didn't show up showing how rude she is.