During kh2, Sora makes a path to the castle in the world that never was through a connection with kairi after she touches namine's hand.
And then, at the end, the door to light appears when Sora finishes kairis letter, and then in the secret ending, after Sora vists the secret place in the credits, he asks Riku what it was. Riku laughs said it had something to do with his heart, further implying that it appeared because of their connection.
So, in theory.....if you put Kairi in the realm of darkness and Sora in the realm of light, or the other way round, you'd have a pathway back?
During kh2, Sora makes a path to the castle in the world that never was through a connection with kairi after she touches namine's hand.
And then, at the end, the door to light appears when Sora finishes kairis letter, and then in the secret ending, after Sora vists the secret place in the credits, he asks Riku what it was. Riku laughs said it had something to do with his heart, further implying that it appeared because of their connection.
So, in theory.....if you put Kairi in the realm of darkness and Sora in the realm of light, or the other way round, you'd have a pathway back?