The curse of immortality - It meant he couldn't die, no matter what, no matter the great extent of injuries he receives, which means he has to suffer if he obtains any extreme injuries that would kill any regular mortal instantly. He would live forever until his body would rot and decay. The only thing that saved him from rotting was the ring that which his brother gifted him, a ring that resets his body state, keeping him young and from decaying.

It was raining softly above the woodland canopy of trees, the leaves swayed above in the soft breeze as you were walking through the whispering woods. You were on your way back to the main city in Mondstat - since you had been out picking some herbs for someone who asked a favour of you - when something caught your eye.

You trailed off the path to investigate, climbing up a slope and walking a few paces, that's when you see it, a tall blonde haired man with clothes you don't regonize from any which nation slumped against a tree trunk, with wounds that should have him dead, but you can see the shaky rise and fall of his chest, his eyes still wide open watching your movements as you get close to him.

Something wasn't right with this man, but you couldn't leave him here all the same. You crouch down to examine his wounds, catching the glint in his eyes, and that's when you see it. The stars in his eyes, that's why he isn't dead; he is from Kheanri'ah, and he has the curse of immortality, which you had read previously about in a book at the library.