The evidence from the passage that best supports the theme that one's true nature is revealed in times of distress is the third one:
"Miserable creature-what have you done?"
It is known that true feelings are revealed in difficult times because one acts without even thinking about it and just say the first thing it comes to mind. Without any boundaries, our words come out with no filter or reasoning period, so this is where we show our true nature.
In this case, in a clear moment of despair, the character calls the other "Miserable creature" and these words show feelings that have probably always been there and that come out in a moment of distress.
