I think maybe mc wished for better parents, a better life and maybe a brother who loves him dearly out of neglect and loneliness as a kid. Then he got into that accident that almost killed him but this entity happened to be there and grant it? Then he became that brother born from the mc’s near death experience and wish? But it doesn’t explain how he only appeared many years later so maybe the mc is also unreliable and actually does suffer from memory loss.
I think maybe mc wished for better parents, a better life and maybe a brother who loves him dearly out of neglect and loneliness as a kid. Then he got into that accident that almost killed him but this entity happened to be there and grant it? Then he became that brother born from the mc’s near death experience and wish? But it doesn’t explain how he only appeared many years later so maybe the mc is also unreliable and actually does suffer from memory loss.