I loved that moment in ... I don't remember which book, one of the later ones (I think Lies Sleeping), when Carey is on medical leave, and Seawoll sits Peter and Sahra down and tells them to take care of each other and look out for each other because the job is hard on you, especially under their rather special circumstances.
If it wasn't clear earlier, that moment is such a nice display of care, and shows Peter as Seawoll's protegé in a way too. And also as someone who doesn't hold with toughing up and powering through.
I really like how we see more depth of him over the course of the series, as Peter recognises that they're definitely on the same side about how they want the police to work.