Jane is understandably on her guard. But, if a fae wants something from her...well, that means they're going to use it against another fae. Which means more suffering for the Fair Folk as a whole, as their rivalries tend to be cruel. Good.

"In that case, what can a witch do for one of your kind?"

She hazards a guess that it's the projects she was involved in while she was a servant. Humans are good for many things when kept on a short leash, she knows: their natural resistance to some kinds of magic and ability to handle cold iron make them good cat's paws for a vengeful noble.