Or maybe it isn't a Nobody at all. Maybe, it's just someone hired by Master Xehanort to keep Aqua from interfering. Because, Master Xehanort wore a black coat when he walked to Destiny Islands to bring Ventus there.
Thanks, to start things off. Here's a video I found posted by a member called Saito_Ikari. YouTube - Kingdom Hearts Birth by Sleep : E3 2010 trailer (HD) It has people in cloak hoods similiar to the ones in Organization XIII attacking Aqua. One of them has an attack similar to Xehanort's.