Playing a pure fae is certainly possible, the line between where they do and do not have free will is pretty blurry from the books. Even in game a negative Refresh cost means you have no free will, but it doesn't necessarily look like that to people observing from outside the NPC's head. The blurryness of the line is why Harry keeps forgetting that sometimes friends of his might really want to help, but can't.
If I were going to play a pure fae I'd just keep my positive Refresh really low and auto-accept any Compels coming from my Court.