Symbolism, Imagery, Allegory
We've all seen that famous painting by J.W. Waterhouse of the water nymphs, right? This one? Water nymphs (a.k.a. naiads) sure are pretty… but do they have your best interests at heart? Not according to Grandpa—he says the pond is a dangerous place because of the naiads. He says:
"The pond can be a hazardous place. Return there now, and you would find friendly naiads beckoning you near the water in order to pull you under and drown you." (5.132)
Yikes, right? It seems the naiads are tricksters of the most dangerous sort. But that's not the only reason why the pond is to be avoided: in its center rests a shrine to the Fairy Queen, a.k.a. "the most powerful figure in all fairydom" (5.136)—and if a mortal sets foot on her island, she might punish the trespasser… but then again, she also might not.
See, for all that the pond symbolizes danger and the very real possibility of death, it also symbolizes hope. When Kendra is the only member of her family who hasn't been captured, she suddenly has a thought:
The Fairy Queen had a shrine on the island in the middle of the pond. Wasn't she supposed to be the most powerful person in all the fairy world? Maybe Kendra could try asking her for help. (17.10)
The amazing thing is, Kendra's gamble works: the Fairy Queen helps her out, and Kendra is able to save her family and Fablehaven all in one go. All thanks to the pond. Or rather, the fact that the naiads and the Fairy Queen decided to let Kendra get as far as the shrine on the island. The pond is a tricky place, symbolizing danger and hope all wrapped up in one.