Possible Clues:

• Greek letter between rho and tau
• "The Sweetheart of ___ Chi"
• Bad mark, losing second character abroad
• Greek version of The Origin of Species
• Letter American servicemen returned
• Author returns to pen good, classical letter
• Letter from Greece turning up a manuscript on a soldier
• Letter in some fraternity names
• Start for Sophocles?
• Disgrace with loss of model character