Zero is a carrier vampire who, even though he is male, can have children. He has feelings for Kaname and the only person he has told is his younger brother Ichiru, who in return is happy his brother found someone to care for again. Zero hasn't told Kaname about his feelings because he is scars of rejection. Zero is very submissive to Kaname and Kaname only.
Kaname may seem sweet and kind to Yuki BUT he only has eyes and love for Someone and no one knows who that is.
There will be boyxboy and Yaoi so if you don't like don't read. Zero can also get pregnant. So mpreg.