"Okay, Alex, it's been fun talking. Let's get you out of my head now."
"That isn't possible."
Like hell it isn't. "I didn't invite you into my brain, and I really like using it undisturbed. Why don't you run along home now?"
"Is no home for me to return to. All my people dead."
That brings you up short. "All of them? You're alone?"
Alex does something in your head that feels like a mental shrug. "Others may have escaped. Elsewhere. Other universes."
So Alex is the only sapient being from their universe in yours? That's awful. And lonely.
"If I leave you, I die. If we find another way for me to be outside your brain but not dead, that would be okay."