Catra seems like one of those characters that seems to happen when:
  • There was a war in the writer's room over how they should end up (Spike from Buffy)
  • They were probably intended to be a good guy, but in the messy middle of the show, it was just too useful to have them screw up/be awful (Ross from Friends, JD from Scrubs, honestly lots of sitcom characters in shows that went on for massively many seasons fall into this trap).
  • They probably were intended to not to be a good guy, but the 'affably evil' schtick won over fans, and they either decided to go with it, or make them start kicking puppies to make sure people remembered they were bad (Cole from Charmed kept showing he would always revert to evil behavior, but the audience kept rooting for him; ST:DS9 had to have a special episode where they reminded the audience that Gul Dukat was a unrepentant tyrant with a garbage self-justification).

And similar scenarios. Thus the parts where they do things that don't feel redeemable-from and the parts where they clearly are intended to be redeemed are both there in series we got. I've heard (cannot back up) that the writers had to fight with Netflix to let the Catra/Adora ship sail. I wonder if the intended ending if they weren't allowed to go forward with it would be for Catra to still be in love with Adora, but realize that she was too wicked for them to end up happily together, and die in some kind of grand sacrifice (Darth Vader style redemption, if you will). They had to lay enough groundwork for that outcome to be plausible, even if some of it (Catra's general wickedness, not just being a loyal soldier to what we the audience know is team evil) makes the outcome they were finally allowed to go forward with feel a little uneasy.