Complex sentence: Although she appears to be a respectable princess, Sara hides a calculating and bloodthirsty nature and uses her time as Garland's "prisoner" to coach him into becoming a proper villain.
Split into simpler sentences: Although she appears to be a respectable princess, Sara hides a calculating and bloodthirsty nature. For this reason, she used her time as Garland's "prisoner" to coach him into becoming a proper villain.