I’m glad I checked here one more time before heading to bed.
The NPC I used is this guy:
Oddly enough, the screenshots there make his eyes appear green. I don’t know if it was the settings on my laptop or if it was changed or what. I did go back and mess with the settings, and they still remained black for me. I remembered to take those screenshots above with higher texture resolutions, so that wasn’t it.
The other NPC, aside from the Blood Prince, I can turn into is this guy:
Who seems to have the same black eyes when I turn into them, but has the green glow kinda on the screenshots on the links above.
Not sure how to explain it. Maybe they changed with the model updates, maybe I’m missing a setting with my laptop, maybe they got changed somehow over time.
Also those mobs are part of this quest:
I believe there is an Alliance version, though they get the more cinematic battle with the Blood Prince whereas the Horde just beat them up in a quest without much fanfare.
Quick edit: There are also these guys, who I can’t turn into them:
Same deal with the eyes, though I can detect some green around their eye sockets, which I kinda can also with the other two. Really weird…
Hope that was helpful somehow! 
