I finished season one again yesterday and realised some things that I am not realised the first time I saw it.
One thing is that Catra united the princesses not Adora/ She-Ra or another princess. After the rescue mission for Bow and Glimmer they were separated because the loss of Entrapta.... but all the things Catra done after this lead to the final event... the attack on Bright Moon and so to the unity of the princesses.
Also we can see that she don't hate Adora or something... she was hurt so much in her feelings and she want that Adora feels the same.
What do you think? - 2 minutes ago