For sure a full blown spirit...
Something about her power keeps him close OR her mother asked him to keep her safe after she died.
Spoilers
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Mister Spirit is the ML. Mother didn't ask him anything, he happened upon on in the woods and broke the taboo by bringing her back to life. That's why he has to rest all the time.
Later on he gives up his immortality to be with her.
AHHH OKAY THANK YOU FOR SPOILERSSS :))
Oh thank God 8ts not one of the brothers or some shit like that...
I can't wait to see morr!
OH LMAO THATS A TWIST RIGHT THERE I DIDN’T THINK HE WAS EVEN AN ML CANDIDATE
Whats yalls theory on mister spirit? I can only assume that he’s either just a spirit or is somehow related to the aehri clan. He has blue hair and all and since it was mentioned earlier that estrella’s mother blue hair, with the aehri’s tradition of incest and strict prohibition of interacting with people outside their clan, we can already assume that they all had blue hair and gold eyes. But mister spirit had pointed ears and blue eyes too so ion think he’s part of the clan