When people talk about 'free will' they are implicitly referring to an uncaused cause - in other words, the ability to act (e.g. to think a thought) without that act being caused but coming from within.
This can be termed Agency - the property of an entity being an Agent, which is self-motivated (in which motivation originates from within, and is not merely passively caused-by something acting upon the entity.
If this is accepted, then it can be seen that free will and agency are not attributes of the 'material universe' of mainstream modern discourse (nor of science - in which everything either has a cause or else is 'random' and presumed to be unmotivated - like some aspects of quantum physics).
For Christians, indeed, free will and Agency are divine attributes; attributes characteristic of divinity.
Since, for Christians it is assumed (on the basis of revelation), that Men have free will and therefore Agency - this implies that Men are to this extent divine; by which I mean actual mortal incarnate Men are divine.
Which means that God made us as little gods - partial gods, gods in embryo: this is simply a fact, and neither a cause for pride or despair.
For mainstream Christians adhering to Classical theology, this implies that God created us ex nihilo (from nothing; presumably at some time between our conception and birth) as Agents , as beings whose wills are independent from him - so, to that extent, we are mini-gods who are out-of-control of God.
The aim is (by theosis) to become more like God but - since we are created/ creatures - theosis can never go very far towards God-ness. It is an eternal fact that only God can create from nothing, and the main fact of our relationship with him is that asymmetry.
For Mormon Christians, Agency is explained by our essence having been in its origins eternal and independent of God - we 'later' became God's spirit children in a pre-mortal life, and then were (voluntarily) incarnated as mortals.
God as the Creator is a shaper and organizer - he does not (because it is impossible) create from nothing.
Because we were agents from eternity, theosis is seen as an (in principle) unbounded process of progression towards becoming the same as God in nature.
The asymmetry between God and Man that remains eternally is not in terms of creative potential - since Man may become a creator in the same sense as God - but a difference of relationship. An earthly Father and his Son may be of the same nature, but the Father remains the father.
Thus: For Mormonism, relationship has an ultimate, vital and structuring metaphysical role.
This is an essentially unique attribute of Mormonism (unshared with any non-Christian religion and un-shared with any pre-Mormon Christian heresy) and this needs to be understood if Mormon theology is to be understood.