I did have a bit of a dark theory at one time about Harry and Elaine being related. But it didn't go down well...which was fair enough. I don't know that I would have been happy if I was right.
In saying that, there certainly was potential for that sort of thing. And despite only being foster siblings....they did grow up together for a few years. It is still a bit weird even if not technically incest.
The theory also had another dark element. Although perhaps I am conflating to separate theories in my head, it was a while ago. Anyway, the other part was that Harry was a victim of child sexual abuse from Justin. Perhaps Elaine was a victim as well. I am not saying this is the case though. But there were certain things that could line up. Particularly in the stuff about betrayal from a trusted and admired parental figure. Not to mention the physical, violent abuse. Let alone the psychological stuff. At the very least there were some possible allegories.
It seemed even more possible in that Jim said Twelve Months (the next book) was about Harry dealing with repressed trauma that we haven't really seen.
There are a lot of questions surrounding Justin. How he came to know about Elaine and Harry. That he was raising them to enforcers. Enforcers for what? Ghost Story, when Justin confronted Harry with a straight jacket, Harry asks, "why?" Justin answers;
That is weird, because he sounded just like Eb and Listens to Wind, in Peace Talks. Morgan and Eb both call Justin, paraphrasing "a bastard who had gotten a hold of Harry." But what if unknown to them, Justin was working under orders from the Council? However Justin miscalculated, infected, he was going to double cross the Council, but he hadn't anticipated that Harry would resist his efforts to enthrall him.
Again in Ghost Story, HWWB seems to know all about Harry, he calls him a "child of the stars.." He seems to also know all about Justin's training of him as well. He appears to be testing Harry's potential, as young as Harry is.. One wonders, if HWWB knew all of this, was Justin infected? And on one hand he was working under orders, but on the other hand because he was infected, Justin had another agenda.. But he miscalculated..
HWWB also miscalculated, he was close to succeeding in intimidating Harry and was proceeding to murder him... But he made a critical error, he murdered poor Stan in front of innocent 16 year old Harry's eyes. Harry had never witnessed anything like that, he knew it wasn't right, he knew Stan didn't deserve to die, it pissed him off.. That,I believe was the true turning point in Harry's life, that was the spirit of Malcolm coming through. In that moment he demonstrated "power over Outsiders."
Did HWWBh miscalculate? Or was that an act? If you look at the result of their interaction two things occurred:
1) Harry learns that it's acceptable to use magical violence to solve problems
2) Harry learns it is sometimes necessary to kill with magic
Look at how that shaped the rest of his life and decisions.
It could be though that HWWBh never expected Harry to be able to discorporate him. He intended those results but wasn't expecting to be banished.
I agree that Justin doesn't add up. His motives were never as straight forward as Harry thought...and the more we learn about him and what was going on, especially from the perspective of others like Morgan, the more it seems he wasn't just any old villain.