i think i can understand why we haven't seen a master xehanort heartless and/or nobody because of what i think here.
sora willingly gave his heart to darkness in order to save kairi while xehanort mearly transported his heart to terra's body instead of just losing it like sora did and terranort didn't do the same like sora did either but unlike xehanort as well, terranort mearly sealed away terra's heart instead of trying to control it since he had at that point realised he cannot control two hearts at the same time so instead he just sealed away terra's heart and left xehanort's heart in control, which is why "ansem" and xemnas didn't appear sooner rather instead of later.
sorry if its hard to understand but that's my theory.
i think i can understand why we haven't seen a master xehanort heartless and/or nobody because of what i think here.
sora willingly gave his heart to darkness in order to save kairi while xehanort mearly transported his heart to terra's body instead of just losing it like sora did and terranort didn't do the same like sora did either but unlike xehanort as well, terranort mearly sealed away terra's heart instead of trying to control it since he had at that point realised he cannot control two hearts at the same time so instead he just sealed away terra's heart and left xehanort's heart in control, which is why "ansem" and xemnas didn't appear sooner rather instead of later.
sorry if its hard to understand but that's my theory.