Pnin is very much the academic professor from in this case Russia, who never really became Americanized. he has set up a routine, and is relatively happy with that, but is still much more comfortable with Russian, and longs for the Russia of his youth. He encompasses many 'professor' types, such as the absent-minded professor, the grumpy old professor, the deeply academic professor... Pnin is very much wrapped up in his own private world, and his mannerisms and ways of being are still so foreign to everyone else that no one disturbs him in his little world.