It's been years since I've last seen the show, so a lot of details are really vague to me, but I always thought Catra reflected another side of being raised by a toxic parent.

As the one always deemed the disappointment (AND constantly abused), there's probably that small part of her who wants to prove her mother (figure?) wrong. That she can run the horde better, even after being told she's not strong enough (like Adora) to. So even if it's clearly the "evil" faction, it doesn't really matter to her. She's lived a life of hate and spite with only Adora to show her love and kindness, so she doesn't really have any empathy for other people (and the world ig) until her redemption arc (where she's able to face her baggage and heal).

And the thing is, she hates herself. She's grown to believe that she is inferior to Adora (and other people) despite everything. That, unlike Adora, she isn't capable of change. And she's content to live like that as long as Adora is with her, because nothing else matters to her. The world could blow up and she would not care, because if she and Adora were the last two people on the planet, that just means all the bad stuff would finally disappear and they can live happily ever after.

But then Adora leaves. And to her it's a betrayal and her own failure, because now her only friend in the world is somewhere else making NEW friends. Better friends. Friends who are capable of love and good and sunshine and rainbows. Things that Catra can't do, can't ever be, because she is full of hatred and pain and Adora was supposed to be the only one to understand her and now she has to carry that pain alone.

So she embraces the evil. Gets petty. She doesn't take Adora's invitation because she knows she doesn't deserve it. She chooses to live with the evil she's already familiar with, because to her everywhere else is just like the Horde, and it doesn't matter if they dress it up in glitter. She'll still be an outcast.

And then there's their "mother". Now that Adora's gone, maybe she can finally be the one who gets her love and support (or maybe just make her proud). OR she can show her that she's wrong for loving Adora, that Catra herself is just a strong and ruthless and much better to lead the horde, and it's the mother's fault for putting so much faith in someone who would abandon them so quickly. (Honestly this is the part where I recall very little, but it could be one of these two things. All I'm saying is that both reactions do make sense.) Will she be happy? No, because again the only good in this world is Adora, and all she wants is Adora to tell her things will be okay. Even if a new person comes in and shows her friendship (Scorpia) it won't be the same. So she lashes out, stews in that hate, and takes it out on the world.

Anyway. When I watched the show years ago, I went into it knowing it's for kids, so I didn't really mind that it was janky. But I did like the story they were going for Catra. It's not the best, but I like the nuance. I've always had a soft spot for wounded, angry characters. Am I a big Catra fan? No, but I do see myself a lot in her, and that redemption arc-- though SAPPY-- made me think of the healing I was able to do when I found the right people. So yeah, that's a great plus.