My parents have custody of my son, if everyone is in agreement can he come live with me without breaking any law?

The issue I would want to look at is how your parents came to have custody of your son in the first place and why you lost it.  It is quite possible that your son can live with you without breaking the law, but there are not enough facts.  You will probably need a lawyer to help.  Perhaps you can find a firm like ours that will give you a free initial meeting to look at such an issue and guide you.