Complex sentence: Second, Shakespeare may have altered Banquo's character simply because there was no dramatic need for another accomplice to the murder; there was, however, a need to provide a dramatic contrast to Macbeth--a role that many scholars argue is filled by Banquo.
Split into simpler sentences: Second, Shakespeare may have altered Banquo's character simply because there was no dramatic need for another accomplice to the murder. There was, however, a need to provide a dramatic contrast to Macbeth: a role that many scholars argue is filled by Banquo.