Zero didn't destroy Rido thus Kaname gave himself up to him. After months of being Rido's toy they have returned to the school for Rido to show just how far from grace Kaname has fallen and reveal his identity as the ancestor. Rido drags them into Kaname's worst memories where Kaname has to keep Zero's identity as his lover in a past life a secret to protect him from Rido's cruelty