One of the best otherkind representations I've found is the changeling in the Danish kids book 'Troldehistorien'
Not the boy on the cover. That's the exchanged - the human who was kidnapped to live among the trolls. The changeling is the one who was placed among humans instead of the exchanged.
The changeling was once a chestnut sapling, transformed into a human by the trolls. Throughout the book we see how the changeling (whose name is never revealed, because trees don't have names) never thrives among humans. He hates talking. He doesn't understand how to play with the other kids. His only moments of peace are among the trees, which beckon him into the woods time and time again
In a moment of desperate loneliness and, what can only really be described as species dysphoria, the changeling digs a hole and tries to plant himself. Having no water at hand, he considers watering his 'roots' with tears. But trees can't cry.
At the end he is turned back into a tree, and the exchanged and the trolls often go into the woods to visit him
