My favored analogy is that of a dog within an electric perimeter fence or on a retractable leash. The dog is free to run as he pleases within the area encricled by the leash or the fence, but that area varies as the owner releases or retracts the leash. The dog can even "negotiate" the length of the leash so some extent by interacting with the owner or may even break loose through the fence (as my friend's dog did) disregarding the negative feedback received in the form of electroshocks. But in each of the cases, the dog's behavior is a function of constraints and freedom within those constraints, both being determined by situation and interaction in that situation.
In that light, the debate of free will versus determinism is that between an optimist and a pessimist about the volume of liquid in the proverbial bottle.
Wojtek