User blog comment:SpookyBoogie27/Light Novel Spoilers/@comment-37.231.114.51-20130209162759/@comment-6253635-20130209163345

Because he helped her best friend Rias out when she couldn't.She saw how hard he works for rias and his never give up attitude.She saw the battle between riser and issei which can make any girl fall.But she really fall for him when he closed the gap between her and her father.