Choicelings inhabit Ackrex Marsh, and are generally unable to live without humid air.
Choicelings will give you a choice between three things: Riches, happiness, or something else of your choice. While their magic properties do let this happen, they always find a way to corrupt your wish. If you ask for riches, they will diminish your happiness until you're a sad shell, while if you wish for happiness, you will be deprived of everything else, leaving you poor and alone. If you choose something else, they'll deprive you of both happiness and money, but, if you manage to create a paradox they cannot handle, your wish will be granted without negativity and successfully destroy the Choiceling. But good luck trying that. The best thing to do is try to avoid them, but sometimes they'll try to follow you until you leave, since they cannot live long without the humid air.
If you really are lucky, you can imprison one. They will do anything to escape and return home, and if you ask for wishes, they will grant them in an attempt to escape, since they cannot grant wishes on themselves. People have used this to get extremely rich, much to the Choiceling's dismay.
Trickets and Choiceling will work together so the Choiceling can grant a wish and the Tricket and mess up everything.