NavySeaStars74

Slightly different idea, Nightmare is captured after a while and becomes an guinea pig for the ministry of magic to test their new obscuris killer potions and spells on. The scientists figure out that He’s unusually strong for an obscuris and learn that if a spell makes him weaker it’s guaranteed to kill other regular obscuri. Dream tries to talk to him a lot and tries to apologize but Nightmare is unable to return back to his normal form because of the amount of trauma he’s dealing with. Dream tries to rally people in order to stop the testing on his brother but the ministry eventually threatens him with banishment plus nobody wants to free an obscuris who managed to kill a whole town in seconds, they just want Nightmare dead. 

Thinking about a story idea where Nightmare is an obscuris (from fantastic beast and here to find them) because of the prosecution that he faced after he and his brother came out as magic wielders. Dream never believed that the villagers could be so mean to him and they got into multiple arguments about the muggles innocence. After a while Dream left their village, completely cutting off contact with everyone INCLUDING Nightmare.And like the terrible people they were the villagers blamed Nightmare tried to burn him alive in the square only to die because he could no longer control his volatile magic. He managed to survive long past the average life expectancy of an obscuris and lives in hiding with his group of friends and his parasite (that gained sentience after some time) far away from his guilt-ridden brother who thinks that there is no way of saving him and is out to kill them all.