Interesting are eastern, mostly hindu teachings. According this such a person can be in the next life as "supernatural" beings if obtains siddhis. For example, through meditation.
In some texts is that it is possible - in some cases - in this life too, but it is very hard.
See Kashmiri Shaivism texts for example. Something is in a novel by Somadeva. Although the terms of the novel, there are opinions of a shivaists.
http://en.wikipedia.org/wiki/Kathasaritsagara
Or a good book is a Taoists Alchemy text The secret of the golden flower, translantion by Richard Willhelm.
https://archive.org/details/TheSecretOfTheGoldenFlowerByRichardWilhelmAndCarlJung
But there are different names. For example chakra Anahata in Yoga is in The secret golden flower called a "fleshly heart"
and chakra Ajna a "Heavenly heart".
So it is about a meditation.
Or in ancient mytsries was called (summoned) pagan gods and goddesses for this reason. See book by Iamblichus
https://archive.org/details/iamblichusonmys00taylgoog
I will go out on a limb and say in the astral it's possible because most things I am told exist there. I assume however you wish to become a physical faerie on this plane. Will. Never. Happen. Study magick to fully understand why but the short answer is magick cannot go against nature. Humans cannot become other creatures by nature, therefore magick cannot change this.
Well, Santa is a phantasy. :-)
But some Fairys realy exist. As a spiritual beings.
https://archive.org/details/doktorjohannesfa00sche
Here is something about summonig since page 136 and followings.
But procedures from this book are not recommended.
Meditation on some fairies is sufficient and mostly without risk.
I would not classify elves and Fae with Santa as the first two are a part of Norse and Celtic Paganism, respectively.
As for the original poster, Otherkin is a legitimate concept in that the soul, spirit, or part of your mind is identified as something other than human, but even Kin know that they can't physically be anything other than human (the legitimate ones, anyway). However, they also believe that you don't "become" Kin because it is a part of who you are, much like you can't truly change your hair color (save for natural aging), but you can still dye it.
