Board Thread:General Discussion/@comment-10608751-20140610024248/@comment-1515612-20140610025354

They never even met each other and the only real connection that they have is Nico. Yes, Nico mentions Bianca around Hazel, but she still has never met her. Also, they do not have the same dad technically. One is Greek and one is Roman. One of the reasons that Nico is listed as a brother is because Nico calls himself her brother and she thought he was a child of Pluto. Also, Hazel never calls Bianca her sister.

It would be like putting Amphrite or Triton as step brother and step mother when there really is no point since they had like 1% interaction throughout the whole series.