Catra and Adora are childhood friends that grew up together in "The Horde", an evil force fighting against the rebellion and training young cadets and soldiers. Even as children, they were always together. They would explore places in the Fright Zone together, cheer each other up and also play together.One day, they got curious and entered the Chamber of the Black Garnet where Shadow Weaver caught them. She let Adora run, but paralyzed Catra and punished her verbally with intimidating and brutal words. Adora told her to stop, but Shadow Weaver kept on going. When she couldn't take it anymore, Adora jumped in front of Catra, leading Shadow Weaver to let them go. This event seemed to have traumatized Catra, as it's one of the memories she sees in the Crystal Castle.
Catra was always jealous of Adora being everyone's fave and the best of the cadets, even though she overplayed it and acted like she was fine with being second place. Adora bought it and never noticed how frustrated Catra was. Later in the series, when Catra breaks down because of these suppressed feelings of jealousy, Adora promises that she never loved being the favorite and that it wasn't her intention of making her feel like that, but Catra is suspicious of her statement.
After Adora leaves The Horde to fulfill her destiny of becoming She-Ra, Catra was extremely hurt and felt utterly betrayed, as she thought Adora left her for her new and "better" friends. This plus the constant manipulation and intimidation from Shadow Weaver and Hordak, as well as her finally being able to be the best, she completely turns against Adora and becomes her enemy. As soon as she became Force Captain and was secretly assigned the mission of brining Aodra back, she did everything in her power to do her job, becoming much more forceful and bitter throughout the series and even attempting to take Adora out herself.In the episode "Princess Prom", Catra and Adora share a dance. Catra also shows up in a red/magenta suit to make Adora jealous. During that dance, Catra is shown dancing with Adora. Catra also dips Adora. Later in the episode, when Catra is about to fall off of the cliff, Adora wraps an arm around her waist and pulls her back up. The fact that Adora grabbed Catra's waist instead of her hand says something about their relationship.
Even though that is the case, Catra is shown to still have some empathy and feelings for Adora, which she's trying to hide and suppress as well. One example would be that Catra gave Adora her sword back and let her flee after she rescued Bow and Glimmer. She's also hesitant when they were in the Crystal Castle together, however, she left Adora in there alone after seeing the memories of how much pain she had to through during their childhood.
- When they were both still at The Horde, Catra slept in Adora's bed with her curled up in a cat-like position.
- They had a drawing of them both on the side of their bed.
- When Adora and Catra were fighting at the Princess Prom, Adora saved Catra from falling off a cliff.
- Catra usually says "Hey, Adora." in a smug voice when Adora comes into her field of vision.
Even before She-Ra and the Princesses of Power aired, people shipped Catradora and were constantly excited for new leaks or trailers involving them. This is because of the immensely popular trope of Rivals to Lovers this ship is following, as well as the show already hinting at their relationship being something more than just friends.
- According to Fandometrics, the ship was the most reblogged ship, the week ending November 19th 2018.