Never punish attempts at talking though problems with too harsh a penalty.
Otherwise you'll wind up with players who just crush or attempt to crush any problem with violence making for a dull hack and slash oreinted game. Plots you work on with intricacies will enver work, because they'll see talking as a way to get screwed over.
That said, I tend to make players wary of what they say even to the point of saying "thank you" to a Fae. (thanks puts them in their debt) So I'd have the fae start demanding favors and messing with tthem some, but nothing too major.
Oh I definitely wasn't going to punish them They agreed to a favor for another lesser fae on the way, I just loved the fact that they setup that relatively harmless (i did "-what-?" thing before doing anything too damaging. i tend to allow my players to go anywhere & try to do anything they want during play & they really enjoy it. I wouldn't punish them, just make them realize that the danger/reward with fae isn't explicit contracts, but even simple conversation.
In the past i've told them things like they need to buy off a compel to say something that mindbogglingly dangerous to a fae, but haivg this harmless one is nice :)
When you have players doing that - ask for a social roll to back it up.The characters that they play do have those social skills at pretty high levels. But what I am talking about here is more what they say than how they say it.
Richard
If your game is a long-term one, wait a few months, then have the Summer Lady make a request, much to their surprise it's a debt. They said "whenever" she wanted help, so an entire adventure could be trying to buy their way out of that recurring debt (possibly involving the Unseelie).Did the characters actually promise to help the Summer Lady? If not, they could take the line that they never did promise to help her. Only for her to "contact him if there is ever a question that might need their involvement".