Who is Raul from The Great and Secret Show: The First Book of the Art and what is their importance?

Raul is the ape-man evolved by Fletcher. He served as Fletcher's servant while he was at the mission, and he later served Tesla in Fletcher's stead. Raul saves Tesla's life by placing her near the Nuncio's last dregs. Kissoon later takes him into the loop and convinces him to allow him to use his body, which leaves him floating around the loop as a spirit. When Tesla finds him there, she pulls him into her body in order to save him, and the novel ends with the two in her.