@Conspiracy Theorist
For a character with such unique qualities, the Archive doesn't get much explanation.
And Jim likes it that way, it means he isn’t hedged in when he next uses the character, which suggests it’s all going to come out in the future. A lot of people were frustrated by the lack of character interaction between Harry and Ivy in Peace Talks and Battle Ground, and I suspect that was deliberate for the future reveal. Instead we got River as confidant and exposition as fan service, a character previously relegated to side stories. It was a bit like Matt Murdoch/Kingpin appearing in No WayHome/Hawkeye.
The likelihood is the same with Bob’s parents, there is some future plot point bound up in it so it makes this a significant topic for speculation.Jim has teased this following speculation upon Bonea coming into being, so he is sitting there gleefully hugging himself.
We know Harry is going to time travel as he will breach every law of Magic, so perhaps we are going to see Bob’s conception or birth or the consequences of them. This is why I think a historical wizard like Michael Scot, is Bob’s Father, Harry is responsible for putting the British Prisoner in Demonreach in the past to frustrate Lea’s continued attention, after religious instruction and iron skullcaps fail. For example Harry needs to consult with the last known authority on the superweapons, but they mysteriously disappeared in the 13th Century, Harry has to track them down in person. Turns out they were in Demonreach all along, due to Harry. That would be a very Harry story.