That's a unique example. [His tone shifts from flippant to more attentive, although the note of gentle teasing remains. He refuses to sound serious, because the answer isn't going to be great.]

If I were dealing with AI possession? I'd isolate it. The artificial brain would be following different paths than the original mind. It would be like two people trying to control the same hardware. You could extract the files that make up the second intelligence from a hypothetical subject once you managed to find them.

But you'd need equipment to do that. [Humor blends into sympathy. It's possible, but only with access to technology.]

I guess you could try to shut it out. That option is less ideal.