on the topic of an XJ-10 we've definitely talked about such a concept before, here's some of the ideas I had brainstormed regarding her;
>overall XJ-10 refines and enhances upon what Jenny can do, as well as introduces new technology to make her more human compatible than previous XJ models
>part of why Nora builds XJ-10 is to introduce a robot that can engage full time in being a global protector, freeing up Jenny more in her civilian life
>XJ-10 is basically a robot version of Olga Pataki in personality, so she's a massive perfectionist
>while Jenny is initially glad to have more free time, XJ-10's sheer seeming superiority over her gradually eats at her confidence and self-esteem, soon leaving her rather depressed
>when XJ-10 realizes this, she ends up being rather distressed at how she's failed Jenny as a sister due to this, which results in her seemingly sacrificing herself to stop a meteor(or some other world ending threat)
>this ends up being a catalyzing moment for Nora to begin realizing how terrible she's been to most of her creations in the long run
>various aspects of XJ-10's design would end up being used for upgrades to Jenny, and eventually new bodies for XJ's 1 through 8(though that's another matter entirely)
>XJ-10 will eventually return as she didn't actually dies
