Some unscrupulous guard/jailer/noble tries to coerce Mollymauk into sex (perhaps by threatening his friends) and gets WAY more than he bargained for when Molly uses Devil's Tongue to make the guy service him instead.

Bonus:

*Molly acting all meek and going along with it at first before he turns the situation around

*rough nasty facefucking mixed in with hair-petting and sarcastic fake gentleness

*a dark interpretation of Molly's sense of fairness and repayment