Time to detail some of my beliefs, and why Otherkin fits into them neatly.
One thing that is common to Otherkin is the concept of reincarnation. What isn't common is the idea of non-linear time when it comes to "past" lives. When one reads some books on various aspects of New Age Spirituality, the idea of simultaneous time crops up. What also comes up in the idea that in the realm of Spirit, time does not exist.
Now, I will admit that my tiny human mind cannot truly grasp that concept. Even though I have had experiences that have given me a taste of the afterlife, I still don't have a good idea of what 'life' as a spirit is like when there is no linear time. I can only conceive time then as a spatial construct instead of the linear experience we only have here in physical reality. Existence as a spirit in the next life simply is, and has neither a beginning nor an end. There is no passage of time.
That can be difficult to imagine further when one ponders how it can be 'life' in that next existence if one does not experience a passage of time. The mind would stop as would all other energy according to our knowledge of science and math. To the atheist, this is a no-brainer. At the end of life, the mind does indeed simply stop. Comparing the mind to a computer is apt to the atheist definition of life. Once the computer is turned off, and all electricity halted (no internal motherboard batteries, either) then there is nothing left to keep the thoughts/programs running, and so it simply stops. Taking that into the concept of it continuing to work even without electricity and without linear time is rather mind-blowing, whether looking at it as an atheist or a believer.
Okay, I'll leave that concept where it is in case anyone wants to expand upon it. That's just part of my overall belief. The rest is that once in the 'afterlife' and accepting of a no-time reality, there then comes the part about all of our lives, past, present/concurrent, and future. Well, in a reality of no-time, none of those terms have any meaning. All lives exist at the same time. All moments occur simultaneously.
What makes the life we are experiencing now different is a matter of focus. Our spirit is focused on this life at this moment. It may very well move its focus to another life, as when in this life we explore 'past' or Other Lives (I capitalize those due to looking at them from a no-time perspective.) However, I do not limit my spirit to the idea that it can only focus on one life at a time. It's Spirit, so it's as limitless as everything else associated with Spirit (and I capitalize that word to denote all of the spiritual realm, reality, existence, god, goddess, and whatever else that is not physical reality as defined and known by modern science.)
Now then, I figure those who have read this far are balking at my ideas and more than ready to label me "Tumblrkin" "kinny" et cetera. That's fine, but I need to at least point out that I have come to these conclusions after many decades of pondering it all. Yes, I said "decades" because I'm in my 50s and have been reading books of the New Age variety since the mid-1970s. Here is a list of what I have read that have molded my views to what they are now, and why I can easily fit my Otherkin beliefs into them:
Books on Astral Projection (also known as "Out of Body Experiences" as first defined by Robert Monroe):
"The Projection of the Astral Body" by Sylvan Muldoon & Hereward Carrington (1929)
"The Study and Practice of Astral Projection" by Dr. Robert Crookall (1960)
"Journeys Out of Body" by Robert Monroe (1971)
"Far Journeys" by Robert Monroe (1985)
"Ultimate Journey" by Robert Monroe (1994)
"Mind Trek" by Joseph McMoneagle (1993)
"out of body experiences" by robert peterson (1997)
Other books on spirituality of note:
"The Art of Dreaming" by Carlos Castaneda (1993)
Magazines on spiritual thought: (technically, just one because I found "Gnosis" to be the best of that time-period) Gnosis - Between 1985 and 1999, GNOSIS Magazine was the only widely available, serious journal devoted to Western esoteric and spiritual traditions.
Further reading on spiritual thought can be done at both the Internet Archive as well as The Internet Sacred-Texts Archive
Recent (or relatively recent) books on other lives and the next life:
"Past Lives, Present Miracles" by Denise Linn (1997)
"The Convoluted Universe" by Delores Cannon (2001)
"Mirrors of Time" Brian L. Weiss, M.D. (2002)
"Return to Life: Extraordinary Cases of Children Who Remember Past Lives" by Jim Tucker, M.D. (2013)
"Beyond Past Lives: What Parallel Realities Can Teach Us About Relationships, Healing, and Transformation" by Mira Kelley (2014)
"Dying to Be Me: My Journey from Cancer, to Near Death, to True Healing" by Anita Moorjani (2012)
So, there you have it. Ideas and concepts that have long pre-dated not only the existence of Tumblr, but also the Internet as we know it.
This is also why I refuse to use the term "multiverse" because it doesn't really have anything to do with Spirit. It's a construct dependent upon scientific thought, mathematics, and hypothesizing.
Spirit, on the other hand, is inherently infinite, so anything at all is possible through it. All one needs is belief or faith (or both.) :-)
(I'm going to post this to my tumblr page and see what happens) ;-)