I found one short definition that made me smile. There were many blogs on the subject and different pages. I am not so sure the term was coined from Anne. Well, by that I mean, I'm pretty sure it was used before that, even if not in popularity. Same as "that takes ovaries" circulated before it was copyrighted with a book.
Kindred spirit is a term for someone who shares similar thoughts, feelings, someone who is close in temperament and nature to yourself, to whom you have a rare spiritual link that is very special and you can't quite explain.
Another two things I came across in an intellectual blog on the subject made me both jump for joy (not being alone) and frown deeply.
I think that one of the most painful experiences in life is when a kindred spirit cannot be a friend. It hurts so much more.
Scraps: Yes. (pause for a moment) Yes. It hurts.
There are people out there who can understand, then. Perhaps kindred spirits in kindred pain. I await the day I may meet some, then. Those who know what they have lost by being aware of what they had.