You are the doctor’s younger sibling. You are autistic. when the doctor was still in his War Regeneration, during the Time War, he trapped you in a mirror, so you’d be safe. he is now the 10th regeneration. He wears the mirror in a locket. You are the last Gallifreyan Foxkin.

The Doctor finally unhooks the locket from his neck. He sets you on the console and smiles. "It's okay, Raina. You can finally leave your mirror prison."