To prove I do still have deep thinky thoughts about SPN...
So I've been thinking about the fact that Weber didn't get the mom dying in flames pressie from the demon for his six month birthday like every other of the kids and reasons why.
The first one that occurred to me was that the demon didn't need to give Weber's life the extra push into suckiness. That the reason for the fires and deaths were to make sure (or at least up the odds) that the children would have sucky childhoods and therefore would be much more ripe for corruption. Maybe Weber's adoptive family was such that his mother dying when he was a baby would have actually made his life better. It's may not have been meant as a clue to anything other than Weber being batshit crazy, but the fact that he grabbed onto the idea of a brother and was so focused on how they'd been "alone" because they'd been split up and adopted does kinda speak of someone who doesn't feel like he has a family at all.
Whether that means he was actively abused, just neglected, or just antisocial and unable to form familial bonds, I don't know. But it's obviously something he's missing to latch onto Andy (and the man with the yellow eyes) so fiercely and possessively.
It's also interesting to note that Weber's biological mother did burn albeit 23 years late and by his own hand. I wonder if the demon had anything to do with the choice of method of her demise.
The other possible theory I had on why Weber's mother didn't get the ceiling fire treatment is that maybe he isn't one of the children the demon has plans for, and that he only came to Weber and taught him to use his powers and aimed him at Andy because he was using Weber as a pawn and that in this case the real prize he was after was Andy. And since Andy ended up killing Weber, that does put him one more step closer and maybe gives the demon an in, a chink in the armour he can wriggle through and exploit.
I don't know; currently I think I'm favouring the first theory, but really I'm going to need more canon information before I can say for sure if either theory is likely to be the truth.