I'm really thinking about Code Adam rn after rebinging the whole thing a month or two ago. It's so good. The characters are great. My favorite is Sita she's so interesting.
To me, she seems like the one who actually cares the most. Atlas seems to care more about the idea of the originals, and Nine is concerned about Atlas and the future, which leads to him wanting to redeem them. But I don't think either of them actually, like the originals for the broken people they are. Its all about the idea of them, although Nine gets a pass for being frozen for years and losing his memory.
But when we met Sita, she clearly kept some tabs on the others. She told Atlas that they weren't the people he remembered. Which means she was paying a lot of attention to how they changed. When she fought Fyra, she still didn't really try and hurt her, then she snapped, and afterward couldn't face what she had done in her rage. She cared about Ramund even as she tried to convince herself she didn't.
I think it might also be part of why she became a model. She said that "It doesn't matter how... I want everyone... to look at me." Part of that is definitely her wanting to be seen as a human, more than an experiment and unused weapon, something looked at and admired, not hidden away in a lab. But i think a subconscious part is her wanting to be seen so that her siblings, the other originals, could always find her.