I believe there to be an error in the dialogue of the town NPC "Pale Morning" in Ala Ghiri:

Quote Originally Posted by Pale Morning
If there's something you need, I'd suggest speaking with Serpent Marshal Brazen Brook. Things tend to go much more smoothly when he's involved.
The character to whom she is referring, Brazen Brook, is an officer of the Ala Mhigan Resistance, not the Serpents, and is wearing a Resistance uniform. No other dialogue suggests he has anything to do with the Twin Adder Serpents.

Perhaps there has been some confusion between Brazen Brook and the character "Serpent Marshal Brookstone" as both their names contain the word "brook"? I'm pretty sure Brazen Brook isn't supposed to be a Serpent Marshal.