Ok I think this might have been said before but what if Ventus was all pure hearted. Remember when Kairi lost her heart, it went in Sora.What if when Ven was erased it was only his body that was erased and his heart migrated to Sora. Then in Hollow Bastion when Sora released Kairi heart, he also released Vens. Ven's heart then went with sora's body and soul making it look like Ven. This would also explain why roxas has emotions because he has Vens heart. It sounds plausible to me.
Go ahead and start tearing it apart.
Go ahead and start tearing it apart.