I in how to write a system, I will be personally teaching you the absolute basic to how to write a system inside of a novel.
First off : AI.
Most novels (even non-reincarnation ones) normally have an AI that controls the system and reacts to the things that the main character does, and here are some things that you should NOT do.
1 : let the system be annoying. These days people don't like sassy systems too much and you'd probably obtain more positive reviews with a more kind system (plus they are way more rare)
2 : this is really a personal suggestion, but have male system AI's. Cuz if it's not a woman then it's genderless, and you want to add as much originality to your novel as possible.
3 : attempt to do what your viewers want and what you want to do. Many viewers may not want the system AI to gain a body but many other viewers may want that, and maybe you too as well. Basically just do what you want with your system, just make sure that you add some originality and don't follow too many tropes.
Anyways, now that we've gotten out of the way things that you shouldn't do with a system, what are the things you should do with an AI?
1 : Make them kind. As I've stated before, sarcastic and sassy system AI are becoming even more popular by the day— and most of the time, more originality means more success. And what is the opposite of sassiness in 80% of the time? Kindness, duh.
2 : provide a reason to why the AI is there. A personal novel that I love (Divine anime system) actually has a reason as to why the AI exists, so please come up with some better ideas other than just ' system ', also better of fact, make sure the system is there for a reason in the first place.
Anyways, that's it for today's lesson.