1) Some of the vignetting is too obvious.
You want to vignette to create an effect but not to show that photo has an obvious vignette.
2) Is his skin supposed to be red? I tried googling the cosplay itself but didn't find anything.
3) I haven't done a photoshoot before but I think it's important that the white balance be cnosistent. In some of the shots you have the background lighting is orange and different from the rest.
4) Don't know too much about the cosplay but the shot I liked the most in terms of colors was this one: http://midnight-dare-angel.deviantar...fter-356841847
Here I can see the actual of his skin and shows that his cosplay is more "real" and not a severe edit.
Overall I think the photos have too much red/yellow cast on the cosplay itself: was this done on purpose?