before his death, matthew was a regualr nephilim. born of mortal and angelic blood, blah blah. he lived in magnolia for quite some time and made plenty of friends while working as an archery and combat instructor. he was even in a relationship. he made friends and enemies and overall lived a hefty life. and quite suddenly, one day, all of that changed. he doesn't understand why or how. he was simply ripped from his body and thrown into some sort of limbo, stuck with only the company of his memories for what felt like an eternity. right up until he crashed back into his body, in a small house that didn't look like his own but felt so. and when he was sure that he was back to reality again, he was frightened out of his mind. it felt like the fire of the sun was corsing through his veins and all of his senses were so hightened that it was painful. he couldn't get his bearings enough to even use his own voice but as he reached out for anything and everything, his hand was taken by the angel raziel who smiled in his face and told him everything would be fine. and the next second, it was. 

as explained to him, he had been taken out of his body by the angel, cassiel per request of a famous shadowhunter who had dabbled in science and was tragically curious. it could have happened to anyone- the death part. yet it felt like a betrayal. his own kind killing him for experimentation. and the story was only getting worse. apparently when the angel raziel found out what cassiel had done, they had the winged creature of heaven exiled to earth, stripping him of his wings and turning him into a human and raziel took it upon himself to bring matthew back but there was irrepairable damage done to his life and memories and raziel had to brng him back with what he could manage. so when matt came back he had a broken past. bits and pieces were from his old life but a good majority of it- including the family he was born into were different. now, he was matthew, famous nephilim abomination. he still had nephilim blood but now he was the product of his father's experiments. and who was his father? the brother to the queen of edom (or the demon realm for those outside of nephilim). his father was a greater demon with a human form who was obsessed with his mother and also obsessed with creating a bridge between angels and demons through nephilim, who were angel's chosen species. it had never been done succesfully up until matt. now he lives knowing that there were multiple stillbirths before him and he has demon blood in his veins that make him an outcast. he remembers everyone he used toknow in magnolia but his relationships with many of them have changed, including the fact that the relationship he was in before no longer existed. and somehow he's an engineer now? and he owns his own business? and he even has two puppies? a lot of this new life was taking him some getting used to but he's been getting the hang of it.