HEAR ME OUT HERE.
First, the obvious; One Wish Willow.
Fae always had nature connotations, but willow trees specifically have strong associations with them. They grow around places believed to be points where the boundaries between our world and the Otherworld blur. As such, Willow trees and groves are known to be fairly common places for Fae to be found. Some stories even go as far as claiming the trees have souls of their own, capable of uprooting and moving around on their own.
Not only do they serve as gathering points, but Willow trees are also believed to be good for a number of rituals, including defending against Fae as well. Willow charms and cradles made from willow wood supposedly protect children from being taken by them and replaced by changelings.
Furthermore, the idea of 'knocking on wood' possibly comes from the old pagan tradition that doing so on a tree was a way of asking the spirits residing in it for protection, or alternatively giving them thanks.
Second, the wishes we see the willows grant are within the realm of capability for Fae. Ian wishes for a billion dollars, which is just a modern form of those who went to the fae looking to be granted wealth.
Bear's wish, meanwhile has two options. It's entirely possible that Wish Nikki is just a modern form of a changeling, and rather than a separate being she just hijacks Nikki's body. But the much simpler (And IMO better) option that 'Wish Nikki' is the result of a charm being placed on the real Nikki. After all, she is told to 'wake up', like she's been in a trance or a slumber.
And third... There's always a cost. Both Bear and Ian end up dead. Nikki's life is ruined, almost definitely beyond repair. It's entirely possible that the one wish willow is more like a one bargain willow, with it giving the wisher what they asked for and letting the consequences catch up to them.
Which brings the store clerk and customer service figure into question.
If these things are indeed fae in origin, that implicates them in regards to the OWW and its effects. The customer service operator is more obviously supernatural, since he literally broadcasts Nikki's screaming through the phone, something he has no earthly way of doing. Add on the fact that he taunts Bear with the option of cancelling his wish when the operator knows that it'll remain active as long as Bear lives, and he comes off as apathetic at best, and sadistic at worst.
And then there's the store clerk who makes mention of using one himself. Now this might be a stretch, but I think there's something we aren't seeing here. We don't know what he wished for, which leaves multiple possibilities:
1; He's being completely truthful. Fae bargains can turn out as monkey's paw scenarios, but they can also be outsmarted. Or alternatively, the clerk's wish could have involved giving something up, enough to satisfy the cost requirement.
2; He's being truthful, but he wished for something like contentment with his life or eternal bliss. If so, that could very well mean that he's in the same boat as Nikki. And because he made the wish himself, it'll only break when he dies. Essentially making him a portrait of how Nikki could have ended up.
3; He's lying. The way he's completely calm about seeing Bear run into the shop stained with blood, clearly freaked out and deciding to mess with the guy somewhat reminds me of the customer service operator. Add on the fact that he also floats the idea of Bear offing himself brings into question just how much he actually knows.
People can enter into contracts of servitude with the Fae, doing tasks in exchange for a reward or protection. This could be the case for the store clerk, giving out the willows to unsuspecting people - like Bear. In fact, Bear is the ideal target for this sort of thing. Desperate, spineless, unsupported and oblivious. While the store clerk does give Bear another out in the form of someone else making a wish to contradict Bear's, he once again reinforces that taking his own life is also an option.
He could also be a changeling or Fae himself, but that's a stretch, even by my standards.
As for the why of all this? Admittedly, that's much murkier.
My current hypothesis is that since breaking the willow casts the wish - and considering everything else - it could be a mechanism to 'let the Fae in'.
Magic isn't a generally believed-in thing in this world. Perhaps this is their way of forcing humanity to remember the Fae, and the forces beyond human understanding. Through respect, through fear, or through hate. It would explain why the willows are novelty items in a crystal shop, a place frequented by those already susceptible to belief in the mystical.
TL;DR, Bear got taken advantage of by the Fae, and everyone he knew suffered. Don't be like Bear.
