User blog comment:SayuriDarling/The House of Hades Official Discussion/@comment-5390473-20140222210344/@comment-3146930-20140223013343

Yes actually. Nico never really got over Bianca's death and spends a large amount of time in the books trying to contact her in some way. He also admits to trying to free her from the Underworld when the Doors of Death were stolen by Gaea. He ended up freeing Hazel instead and a few times almost calls her Bianca. There seems to be a lot more hinting at having a crush on Bianca then having a crush on Percy.

You could also say that Bianca is the only person that Nico loves, but not in the way most people see love. A lot of the time with Valentine's Day, people think it is only for couples. However Valentine's Day is a celebration of love in all its forms, including the love between family or friends. I mean I love my dog, but I don't plan on marrying her. If Cupid is the god of love, he should recognize all forms of love. Now obviously in a young adult book, Rick would pick homosexuality over incest, but there is a lot more pointing to Nico loving Bianca over Nico loving Percy.