#That one route where she can “hear” the internal dialogue is just her deciding it'd be funnier to finally acknowledge it.

[maybeophe]

I like to imagine that all of the Voices are spoken aloud through LQ, so the Princess just watches this guy cycle through various different speech patterns as he has full-on conversations with himself. And she just politely ignores everything said until it's spoken in LQ's actual voice (the player's choices).