Post History
I'd say for this to work, there should be sufficient information before this point for the readers not to see the antagonist as a bad guy. Machiavellian perhaps, but not evil. Then, for the antag...
Answer
#4: Attribution notice removed
Source: https://writers.stackexchange.com/a/34242 License name: CC BY-SA 3.0 License URL: https://creativecommons.org/licenses/by-sa/3.0/
#3: Attribution notice added
Source: https://writers.stackexchange.com/a/34242 License name: CC BY-SA 3.0 License URL: https://creativecommons.org/licenses/by-sa/3.0/
#2: Initial revision
I'd say for this to work, there should be sufficient information before this point for the readers not to see the antagonist as a bad guy. Machiavellian perhaps, but not evil. Then, for the antagonist, it should indeed be the logical solution to let your protagonists go. I mean, they fought against him. It isn't logical to send a message that "fight me, and you will be generously rewarded". It also makes sense that if the antagonist chooses to let them go, he would make sure to render them powerless to ever oppose him again. And finally, you would need to address how your protagonists feel about getting what they wanted handed to them on a silver platter by the antagonist. Are they suspicious, expecting some treachery? Remorseful for having fought a guy who turned out not to be so bad after all? Angry at getting "pity", rather than having won their rewards? It wouldn't feel so much as an ugly Deus Ex Machina if all the implications are addressed, I think.