Naminé and Roxas appear to be of a similar nature, not quite supposed to exist, yet still existing because of someone else. While Roxas is the Nobody of Sora, she is actually a "special Nobody" born from Kairi's heart when it left Sora's body. However as Kairi had no darkness in her heart, Sora's body and soul were used in Naminé's creation. As a result of this, she had none of Kairi's memories. Because of this, DiZ states that Naminé's birth was special and her powers could only effect the memories of Sora and those whose hearts are connected to his, which was why she was used by the Organization.