"Four deserves to be in that moon, One was trapped in there for so long"
Then she knows what it's like.
Just because Four tried to protect everyone else and thought the best option was to trap One in a moon doesn't make it justified for One to trap Four in the same moon, they're doing it for different reasons.
Four and the others did it because they were scared, for what we can presume to be ages before is that they lived a pretty peaceful and mundane life so having one of their own suddenly shatter and become a fractured value by the hands of another, it would be scary.
They were doing what they thought was the safest option and that was taking One's power from her and putting her in a moon.
One put Four in the moon because she was petty. She was angry and hated Four and put him in the moon. No other reason other than selfish.
You are allowed to feel bad for both characters but you have to understand that One let her insecurities, jealousy and inferiority complex get the better of her which almost resulted in the death of Three, when trying to reverse what she did, she ended up essentially mutilating Three permanently. All because she got jealous that she wouldn't be the one in the spotlight anymore.
Does One regret what she did? Absolutely, she wants to fix the mistake she made.
But that comes at the cost of her hunting down and hurting others to steal their power to fix someone who will never forgive her. It's all for nothing. Three will never forgive One, especially after this. She's hurting their friends to fix a mistake she was never going to be able to repair.
Pencil and One are one in the same. One is right when she says they're alike, but not in the way she realises.
They're both trying to fix the mistakes they made by going to the extremes to reverse it, but you cannot fix something you were never going to be able to repair. You've done too much damage already. And you trying to go to an extreme to fix it is doing more harm than good.
In the end, it's a selfish endeavour. For the both of them, and that's why they're both so well written. They don't realise their own downfall.
