Who is Peppercorn from Tevye the Dairyman and the Railroad Stories and what is their importance?

Peppercorn is a young intellectual and student who is impoverished. He becomes friends with Tevye and tutors Tevye's daughters. Peppercorn gets Hodl to agree to marry him, though because of his revolutionary activity he is about to be sentenced to jail. Peppercorn marries Hodl and is then sent to jail. The couple reunite when Peppercorn is sent in exile to Siberia.