Nobody hurts Nemu. No one. He doesn't, even though he knows they think he does. Sometimes, things happen that cannot be helped. Sometimes, there are things he just has to do. He is more important than her because he is the one who can bring her back to life. That is something that if he were dead he would not be able to do. She cannot bring him back, so once he is gone, that is the end. He cannot allow himself to be killed, because it will not only be him that falls, but Nemu as well.
And he knows it. He does not know if she knows it, and he knows the others do not know it. But it does not matter to him. He will use her to protect himself to protect her. Whether she knows it or not is none of his concern. It does not matter. What matters is his craft. He works at it, bringing it closer and closer to perfection, but never reaching it. He doesn't want to, anyway.
But that does not matter. He will never gain the respect he deserves from the others anyway. They just see him as abusing Nemu. He does not abuse her. He makes her stronger. That's what happens, in any rate. He hits her so she will learn. He uses her so that she will survive. It is difficult to kill Nemu. He will not allow that to happen, as long as he is still alive. She matters to him. Not only as a priceless creation, but as something more. He cares for her. She is his daughter, and he cares.
But he is different from them. He cares for her, but in a different way. He does not show concern, or the normal type of care. He does not buy frilly little things, he does not bring her out or treat her. He treats her as a relatively normal person. Her salary is hers to spend, though he knows that she does not spend it. It has been residing in the fastest growing bank in the whole of Soul Society since the year she became his lieutenant. He knows because he deposited it. He knows Nemu knows where it is. He allows her to use it. Whether she does or not is a different matter.
And he knows that the others think he is withdrawing her salary to do research, they think that he is abusing her, they think that she is nothing to him. But it doesn't matter to him. What he does works. Nemu is stronger than ever. His method does not need to be improved. He is content with the knowledge that she will be able to survive without him. He is content with that knowledge, because he knows that one day, there will come an enemy which he will not be able to stop, which he will not be able to avoid, which he will not be able to kill. And one day, he will die. He knows it. And he knows that Nemu probably does not care for him one bit, but it is merely out of habit. It does not matter to him. Not really.
But maybe it does, just a little. Sometimes, on a bad day, on a day when his experiments go wrong, when he finds that there is no one to ask, no one to approach, no way to drown his sorrows, he feels lonely. There is simply, no one. He does wish that Nemu would truly care for him, but he knows it is not possible. For her to be strong, she has to learn. For her to learn, someone has to teach. And she has learnt all she possibly can from books already. He is the only one who can teach her. And he does not understand the intricacies of being sweet and kind and caring. He teaches her in his own way.
And as such, she will not truly care for him. And he knows that. But it doesn't matter. He cares for her. That is enough. He will strike down anyone who dares lay a hand on her. He does because he cares. And he will not stand for anyone to sully his most precious creation, the one person in the world who might possibly understand him. He will not have it. He simply will not have it. Nemu means a lot to him.
It is selfish, in a way, but Nemu is his, and his only. No one else is allowed to do anything to her, because they shouldn't, really. And they do not understand. They do not understand him, they do not understand her. And if they do not understand her, then how can they say that they can be better to her than he can? He does not force her to wear the shorter skirt because he wants to ogle up her ass like some of the shinigami say. He does not force her to be submissive because he cannot get laid otherwise. He could not care less. Nemu is dressed as she is because it is functional. That is how she fights. Long pants, the complicated folds of the typical uniform would only serve to get in her way.
She is built to have a higher threshold for pain, to care a little less than usual about herself, to be strong, to be fast, to be good, not because he pursues perfection. He wants her to be capable, to be functional. He does everything he has done to Nemu for a reason. They do not understand the reason, and they will not understand the reason.
And he knows that. He knows all this, which he keeps inside himself. He locks it deep within the part of him that still feels emotions, the part of him that he keeps masked behind the layers of technology and progress. He keeps this all inside, and that's how he wants it to be. Oh yes, it would be wonderful if there were a way in which he could improve their views of him. It would be wonderful to be seen as more than a mad scientist.
But he knows that it is not possible. He cannot do it. It cannot be done. And so, he will remain the same. He will remain Mayuri Kurotsuchi, Taicho of the Twelfth Division of the Gotei Thirteen. He will remain a scientist, a researcher, and a father. That is who he is, and who he will be. He does not like it, but really, he is too far gone to care, too far gone to be able to do anything.
Some mistakes can never be fixed.
Some things can never be forgiven.
He does not think that Nemu will ever forgive him.