Becoming fairykind means that the Fairy Queen's and her fairies have infused a person with their magic. Ordinarily, a mortal must drink magical milk to perceive magic, though the effects wear off after a nights rest. After becoming fairykind, or a handmaiden of the Fairy Queen, a person will exhibit these magical properties indefinitely.
Once fairykind, a person is immune to distractor spells, can understand the Silvian language and other related to it, can see in the dark, and become resistant to mind control. A portion of the magical energy that naturally dwells in fairies now dwells within the person, and he or she can recharge magical objects and transfer some of that energy to fairies. This person can also command fairies in the name of the queen to offer help or divulge information.
Being fairykind is a rare occurrence, even more so than being "fairystruck". Kendra Sorenson is the only known person alive today who is fairykind. The Sphinx is the one who tells Kendra the truth about her being fairykind, and not fairystuck.