he's the guy harry killed with the mage hand..
I don't have a copy of SmF atm. Wasn't it in the first fight against Thorned Namshiel at the Shack that Harry was suddenly gifted with Soulfire?
If it was, is this another huge clue in hindsight? Uriel's way to contribute in the fight against Nemesis?
Thorned Namshiel is the prime subject for the Denarian to throw around Hellfire during the attack at Arctis Tor.
The motive behind the attack is almost certainly Nemesis-related.
By recent woj, the Fallen themselves can be Nemfected, but it would be sort of impractical. So if Thorned Namshiel was Nemfected, it was probably the host. It almost has to be the case, or Vadderung and Mab would have a major problem with
Sir Baron now. I am sure that both are able to see exactly who is with him. While Mab is more vary of Marcone now, I got the impression at the end of BG, when she discusses him with Harry, that she still counts on him to be an ally.