Ian Arnstein

From S.M. Stirling Wiki

Ian Arnstein is a viewpoint character and hero in the Island in the Sea of Time trilogy. He's a university professor from the University of San Diego (a small Catholic University) in San Diego, California. He teaches ancient history, and is also a published author and becomes the Republic of Nantucket's first secretary of state. He marries Doreen Rosenthal.

Ian is one of the first people to suspect what has happened during the Event and gets the rest of the people of Nantucket to think long term based on the presumption that they are permanently transferred in time or space.

It is suspected that Ian is a thinly veiled Harry Turtledove.