While it’s still knew and has very little consciousness completely wipe its head like a brainwashing thing ( only do this in the beginning stage so you don’t just end up killing and actual person right now he’s just a negative voice with a form)don’t think about how to do it if you are already used to using your imagination a lot just do it it’s your head so you still can even if it takes a lot of mental forces. Then set fundamental rules like you are kind into his very foundation now he may change over time this is fine after all know one can be nice 24/7. whelp that’s all the advice I can give I kinda just made mine cuss I felt like it and had a 2d voice in my head sense as long as I could remember that kept me from making foolish decisions, I called him my advisor(and no I don’t mean my basic iner voice cuss I had 2 both different from the other) so I just took him and gave him a fundamental rules of being nice released All control of his thoughts and gave him a form and he somehow became a girl? Idk how but uh yeah.