[ Hiei turns a distinctly unamused stare Scott’s way as he says he wouldn’t have thought. Of course there are many demons who look the same as him - other than perhaps an odd choice in hairstyle or body art they could be mistaken for human. He chooses to cover the third eye in his forehead for obvious reasons, and since he still visits the human world Kurama occasionally convinces him to shorten his claws.

… but Hiei being Hiei of course has to have something to say about it. ]

Am I meant to be an ugly, warted and horned grey thing as a demon?

[ he will never not take the opportunity to hate on a grey demon, and with that little annoying exchange done he decides to simply make a point.

Thrusting his hand and arm in to the fire with a new type of certainty, his bindings catch fire and begin burning away quickly. Hiei’s face is an equal mix of careful vigilance with a certain smirk as he does so, the lack of burning sensation already tell tale that this should turn out how he thinks.

Of course, his only real experience with a burn had been using the darkness flame for that first time, but he still remembered it. The dragon tattoo beneath it comes in to view, but his skin is untouched even as smoldering remains linger before floating away as soot. ]

So my theory is correct. Which means the others will have some measure of their ability too.