⟩ Tell me have you thought of any questions since the last interview?
It is not uncommon for second interviews to start by asking if you have formulated questions about the position since the first interview. It is always a good idea to have two questions prepared. You do not want to start the interview with an answer of "Nope, I'm good." If you cannot come up with any good questions, one that always goes over well is "What do you consider the overall philosophy of the department".