Moe

So, the origin story is pretty straightforward. He was a weird kid, then he snapped and killed his adoptive mother and "sister". Afterwards, he disappeared. So he's not a ghost or a demon, just a maniac.

Why, then, does he have superhuman strength and invulnerability? Is he just supposed to be a mass of slasher villain tropes turned up to 11? Because he's too powerful to not be supernatural. I'm just not sure if it's an intentional play on the genre or simply lazy writing.