Bicameral mind

I didn't have to wait long to have a talk with Arne. He took me out driving yesterday, since my father reminded him that I was taking the G1 road test at the end of the month. I walked over to Arne's current temporary workplace, the Milborough Durbar in Miniscule Mumbai (Milborough's half-block sized Indian neighbourhood).
Arne was cleaning up the plates after the lunch buffet rush.
"Arne, I've got a problem," I started.
"I know. Just go really blonde and wear lower cut tops," he said.
"Damn it, not that kind of problem. Duncan is under some kind of mind control and I can't figure out what's wrong." Arne didn't look very impressed.
"Don't any of your weird friends do Wicca or something? Can't they just put a reverse spell on him?"
"Zapata's already tried that, and it didn't work. Charles Wallace and I think that it may be a type of hypnosis, and, well, Arne, you're our only hope." Arne started gloating. "Stop audibly gloating."
"I'll think of something while I'm running the dishwasher. Have a seat and don't touch the butter chicken, it's been under the lights too long." Arne then went into the kitchen. After about twenty minutes he returned, and said he'd tell me his plan once we drove around town a few times.
After our third trip to the Beer Store to return his empties, Arne said that he needed some background on the whole thing.
"Who's the previous boyfriend?"
"Jeremy Jones. He claims that Eva was invisible for a while this spring, too." Arne's eyebrows went up.
"Invisible? That's strange. I really need to talk to her--I could use her in my act, once I find a venue."
"That's not helping. You're supposed to be stopping her from mindcontrolling Duncan, not giving her a job." Ultimately we settled on him meeting with Jeremy and then later doing first-hand observation of Duncan's interactions with Eva.