That's new. The only name we had for her before was Das. I'm surprised they'd spoil her real name so soon. In the lead-up to the series premiere last year, they were adamant about referring to the characters solely by number so that the revelation of their real names at the end of the first episode would be a surprise.
A very impressive premiere. They've really opened up the storytelling and added a lot of interesting new character arcs and worldbuilding, as well as new characters. Nyx (Melanie Liburd) is gorgeous and strong, and I can't wait to see more of her.
Another novelty: The episodes have titles this season, not just numbers. This one's "Welcome to Your New Home."
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It felt like a small reboot to me not only the episode titles but they were introducing character names the entire time. I don't recall Two, Three and Four using their gimmick and referring to themselves as such in the prison scenes.