Helorm actually chuckles. Part of her is starting to go along with the pretend reality, especially given that she's sitting right next door to a psychiatric hospital and should really have been sedated by now. [He said 'tsi-imbi',] she tells the voice in her head, and hears a startled laugh from the other end.
"The voice in my head says to tell you that you're not insane either," Helorm says a moment later. "Wait. How does the voice know what tsi-imbi even means, if it's from an alternate civilization that diverged long ago?" If she's going to take this seriously as reality, there are Many Large Questions here.