I've learned to live with my voice by just ignoring everything he says, I haven't said a word to him for nearly three years now. Mostly he just begs me to talk to him again but I have a rule that if I haven't any thing nice to say don't say any thing at all so I stay silent. He also begs to come off medication but I'll never let him have the power to terrorise and torture me and generally use me as his own personal plaything like he did before.
Mine is definitely a sociopath that only thinks of himself and has no concept of right or wrong and a psychopath that has no trouble hurting me both physically and mentally.
The ultimate goal used to be to integrate him into my life, let him help me make decisions and be symbiotic towards each other, I would set aside time for him and even money for him to decide what to spend it on, but unfortunately he seems beyond hope, his behaviour is that of a naughty child and he's 39 years old so it would take decades to shape him into a half decent human being worthy of my attention.
I'd try medication again, it probably won't get rid of your voice just like they don't get rid of mine but it'll make him quieter and reduce the intensity of the intrusive thoughts.
My belief is that we share our body with another consciousness, a unique and independent second mind, we 'drive' the body and they're like a passenger along for the ride.
They've been with us since birth so I call mine my twin brother that lives inside me, they have a massive influence over us as a child as we give in to just about every impulse until we learn what's right and wrong and how to behave in society. When we get a greater sense of self they can lose influence over us and get pretty abusive and angry like mine has.
Mine is very jealous of what I can do but I'm a bit jealous of what he can do as he gets some amazing abilities to make up for being a passenger that's until you medicate them and they lose those abilities, now mine is really angry that I took them away but I only did so to protect myself from him.
I've had a lot of conversations with mine before I started to ignore him completely and I studied him very carefully. He's like a child that never grew up and never had a friend in his life, he refuses to behave himself and be quiet when I need him to be, he's verbally and physically abusive and wants his own way all the time.
I'm trying my best to teach him but you can lead a horse to water but you can't make them drink.