"That makes sense, then." After the Time War, the Doctor became battle scarred, irritable, angry. He'd spent centuries fighting, then living with the guilt of his actions, which culminated in the horror of destroying his own home planet along with the rest of the Time Lords, and opposing Daleks. He was not in a good mental place, so it stood to reason that the show also got darker. "You wouldn't want to know about the Time War, anyway. It wasn't my brightest hour."
Back to Jemma, a more neutral subject. "Is that what you're teaching here, biochemistry? Were you and Fitz also professors in your original universe?"