Kingdom Hearts II When was namine created...?

[Spoilers for KH1, KH:CoM, and KH2]

Kairi didn't have the darkness in her heart needed to create a nobody; therefore, lack of that darkness would have made it impossible for Namine to have been created when she passed through Sora in the Secret Place. That's when Sora recieved Kairi's heart, but that's not when Namine was created.

When Sora stabbed himself with the Dark Keyblade, turning himself into a Heartless, he created two nobodies: Roxas and Namine.

Roxas was, of course, the result of Sora losing his heart. That part is simple enough; but Namine's existence is a bit more complicated than that. Namine was created using Sora's heart -- Sora's darkness. That is the reason why she can manipulate the memories of him and those around him. Namine told Roxas he was never supposed to exist in KH2, which is true, but her existence is even more unstable than his.

[Spoilers end here]

Hope that helps...My shot at sounding smart XD.

 

Kairi's heart went inside Sora's body right?Kairi cannot be turned into a heartless because she is a Princess of Heart,that is why she managed to revert Sora into his original form.

When Sora stabbed himself with the Dark Keyblade(I forgot its name)to release Kairi's heart,he lost his heart in the process and turned into a Heartless.Namine and Roxas were born at the same time.Roxas was created like an ordinary nobody.Lose your heart.Like the person above me said,Namine's birth is a tad lot complicated.

Roxas is special because he does not have any memory of being Sora.Namine arranges memories.So Namine and Roxas are Sora's nobodies.Yes.Namine is the nobody of two people.Roxas should not even exist.

In CoM,she said that she was Kairi's shadow.This will be complicated.

A new mystery about Roxas is Axel talking about Roxas' heart.That is yet to be solved.