User blog comment:TheBlueSlug/Who should issei end up with?/@comment-24098614-20131127045237/@comment-1359322-20131127061603

Well that's cause Issei pitied that she suffered so much in the past that he feels like he need to protect her and looked at Asia like a younger sister figure, of course that changed after Asia manages to pull her relationship further but Issei still views her like a younger sister but also start to look at her as a girl just not at Rias or Akeno's level.