My son wanys to live with me not his dad and he is 12

Can we assume there is a court ordered custody order that says the sone lives with the dad?

If so, you need to petititon the court for a modification of that order.

If you also want him to live with you then go to court and petition the judge for a change in custody.

Yes, in child custody cases, it is the court that decides where the child lives, or at least who has phsycial and legal custody of the child. So at this point we will have to assume the father has custody. Can we ask why, since it is not normal for a father to have full physcial custody? So was there some issue in the past that caused him to have custody.

The courts will look at what is best for the child but will also ask the child what the child would like.