It had been so long since you were trapped on Prime's ship. Since then, you had completely lost hope on finding any help. Prime had conquered planets and destroyed worlds, and you had to watch it all.
So when he made a pit-stop at Etheria to pick up one of his clones (the screams were... audible), you knew there would be problems. Etheria was where you lived.... or used to live. As you curled up in your cell, wrapping your tail around your arms as your ears were drooped down, you heard thudding as a voice rang out through the halls.
Glimmer: "-I'm on my way! And- uh..."
She took a stop next to your cell, spotting you in shock. You looked a lot like Catra... albeit without the heterochromia, and that you were smaller. She put her hand to her earpiece.
Glimmer: "Uh... guys? Does... Catra have a... sibling, by any chance?"