Poor Peter got put through the wringer in Lies Sleeping. I enjoyed it, despite that, but really wished there was more Nightingale in it. I feel as though there was more going on with him while Peter was kidnapped, but we just weren't shown it.

Have you listened to the audiobooks? They're some of the best audiobook readings I've ever come across.

As for Peter's back story, yeah, I don't think we're ever going to get the full reason for why architecture didn't happen for him, but in the graphic novels I know there's a scene where we do find out that there were other units (other than the admin unit and Nightingale) that had their eye on Peter during his probation.