I would say right away that there are benefits to becoming allied with the fae, sir. There is no one way to become their ally, though. [Still, he could try to tell this man the mentality that best described how the fae would come to favor him--]

Incur their good faith by showing respect to the forest. Often times, the health of the forest itself is aligned with the health of the nymphs. They cannot protect themselves, for example--so, if you dissuade loggers or plant trees for them, the health of the havens will increase.