I believe we are rather channelers of will than containers of will. Will does not arise from our conscious rational intellects, or even from our unconscious minds. And free will belongs to the universe as a whole.
Predictability is another matter. Individual free will might be negligeable or even non-existent. But since "will" belongs to something greater than life and humanity then causality must also expand to the universe as a whole, and it becomes impossible to make absolute predictions about anything outside of abstract logic and math - in fact, the same reasoning can be applied to non-living objects.
We can, however, make reliable probabilistic predictions, which are relative predictions.