In TPOT 23 two says One doesn't want a "repeat of Three." That with Four saying One is evil made me think. I don't think one is evil. I think part of the reason one feels so Nerfed this episode is because the crew wanted to make it feel like she didn't want to kill anyone. Correct me if I'm wrong, but Three and Liy are the only two people we see one directly kill, at least in a physical way like Liy. With the deleted contestants it'd be easier to separate from the action of doing it, where with actively killing the contestants it wouldn't be.
When Leafy comes into One's room and refuses, she just sends her out, same with doughnut. She even keeps four alive in the moon along with the other algebraliens (not in the moon but alive.)
I end up forgetting the scene in TPOT 20 where she goes back to the algebra (or whatever it's called) planet, but it has something to keep in mind. The moment she comes back there she panics, having flashbacks to everything with Three.
If just being in the same place reminds her of something she really doesn't want to remember, it makes sense that doing the same action would too.
"Ok but like whyyy does One feel so scared of doing another three?" You may ask. (You ask that because I told you too and it's all I could come up with hush.)
Reason One: That event led to her imprisonment, being alone in the moon for 16 years. That seemingly made her go a little crazy? I mean everything she does in TPOT she seems very on edge, and being alone for 16 years has to do SOMETHING to you.
Reason Two: One is guilty about killing three. Her whole thing after that event is constantly trying to fix Three, and I do believe that's because she feels guilty. A lot of other people have said she just wants to fix three because she thinks that will fix her friendships with the others. That COULD be true, but I don't fully think so. She keeps the notebook Three had, and just her emotions and words after that feel too real.
So yeah that's my Yap! There was another part of this then I realized how long this was so you'll probably get that soon.