Ok well we all know that ven looks just like roxas.But how? well i have a theory when ven got frozen by MX his body got trapped and Terra or Aqua had to save him.But the only way to save him was by realeasing his heart and soul leavng the body behind.Terra took his heart and soul to the destiny islands.and in the leaked trailer you see Terra watching two boys play.Well i believe that those two boys are Sora and Riku.Somehow(i dunno magic maybe?) he gave it to sora.and that my theory (also im new to the forums but have been coming here for years so dont flame)