What I mentioned about Aeria's speaking style becomes a little more apparent when Aeria and Laermont are side by side. I really liked how Lea and Laermont both got deeply interested in each other, two enigmas trying to crack their own mysteries through the lens of the other.
I will note that Demvir can very much die. They can even bleed out. Replenishing blue blood can be a challenge, because demvir aren't biological, and so you can't just eat oranges to build your fluids back up. Appealing to Castus can help from a magical side, but barring that, a transfusion from other demvir (live or otherwise) may be the only option without long-term repercussions.