Sounds like Datu is experiencing dissociative feelings, or a detachment from his own self, when he talks about watching from the back of his mind.

Just for kicks: There is an interesting connection to Haitian Voodoo zombies and dissociative drugs. One ingredient found in the zombie powder by Dr. Wade Davis (The Serpent and the Rainbow) was tetrodotoxin, found in puffer fish. The other was the plant datura or jimsonweed (Zombie Cucumber). This plants can make a person prone to suggestion in addition to dissociative feelings. http://zombie.wikia.com/wiki/Zombies

Now, just waiting for someone to make a connection based on the fact that the first four letters of datura are d,a,t and u.