ANSWER: The two lines that shows that Emperor Nero was ruthless are:
1. “Bring him to me here this instant,” said he, “and let Marcus with his knife and branding-iron be in attendance.”
and
2. "I have half a mind to burn their town about their ears so that they may remember my visit."
These were the two lines from the excerpt which states the ruthlessness of Emperor Nero. He wanted to kill the man because he became more popular than him amongst the common people. Emperor Nero could not bear this popularity which is why he wanted to burn the village down to make his presence remembered.