The pixie is a good pest that appears randomly on your plants. Some plants seem more prone to getting them than others. All plants like pixies and they cannot be removed by pest spells. So congrats to your friend for having a pixie.
Taking good care of them, stay on top of pests and needs, and / or having more than one item they like, i.e. my cactus bears like sand piles and garden gnomes. I take good care of them, and always get pixies.
one time, i was snaplion farming (farming a snap dragon together with dandelions) and my snap dragon got one. later, my venus fly trap got one. now thats what i call luck. moolinda wu must really like me