Out of curiosity, how does this work if it's the other way around. If Mary the PC knight puts the aspect on the Demon keeping him from leaving the room? Does the GM give him a fate point if he complies and make him spend one if he wants to buy out?
Are you talking about compelling the demon? If so, yes, it would receive a fate point. Either from the player or from the GM's bottomless pool.
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Fate point use:
- Invokes are fairly straight forward, the invoker pays* a fate point and gets a +2 bonus to the relevant skill. If the aspect used is attached to the victim of the skill, said victim receives* the fate point.
- Compels are more complex in leaving room for negotiation of details. Once details are decided, the compeller offers** a fate point to the compellee and the compellee decides whether to buy it off by paying a fate point (in which case the compeller keeps both fate points) or accept both the fate point and the compel which comes with it.
*Newly created or discovered aspects get on free 'tag' - an invoke which doesn't involve a fate point changing hands. Or...
**...the newly created aspect's tag may be used as an 'invoke for effect' which initiates a GM compel. A fate point from the GM's stash is offered to the compellee. If bought off, both fate point's go to the GM's pool.
The book complicates it with some situational jargon but the above is what it boils down to. The difficult part is negotiating the details of the compel.