So Hiei is a telepath. A very lazy telepath, admittedly, but still. His Jagan eye (the one on his forehead thar) gives him the power to do all sorts of fun things to other peoples' heads. Here are the basics, and you can tell me whether or not he can do this stuff to your character. :3
Hypnosis: Can he look into your eyes and make you do his bidding?
Hypnosis part II: After he hypnotizes you, can he alter or remove select memories?
Actual telepathy: Can he speak directly into your mind?
Suggestion Planting: Can he plant a suggestion in your mind (eat at Urameshi's!)?
Mind reading: Can he take a look at your thoughts and memories?
And it's not really telepathy but still related to the powers granted him by the Jagan: if your character is a demon, can Hiei sense them?
ETA 5/12/10: This isn't something I'm asking permission for so much as it is a heads-up (perhaps backwards permissions?): In addition to his previous powers, Hiei now has the spirit of the Dragon of the Darkness Flame living inside of him. That's basically the personification of the fires of Hell, so if your character can sense demonly things, supernatural things, or has an affinity with dragons...they will probably be pinged by Hiei's presence in the City.
Also, the dragon exudes an evil aura that makes Hiei seem a hell of a lot less trustworthy and a hell of a lot more creepy. (This is the thing that supernatural-types will be pinged by.)
IMPORTANT NOTE:
Hiei very rarely uses these powers, even in canon--in fact, the only reason he would use most of them would be in the case of plot. But I feel that having a permissions post to prelude that is a very organized thing to do, which is why this exists. If you think these powers look interesting (they are, and Hiei really only used them for work in canon) and would like to talk plotty things, you can hit up
this post or ping me on AIM, username ERT KEY.
Thanks a bunch, guys!
ETA 5/27/10: There are some features of Hiei's anatomy that are...unique to him/demon kind in general. Because I have discovered that I am bad at remembering to mention these things in the heat of a thread (where it could potentially be important knowledge), I'm going to list them here. Consider this a short reference for characters who are psychic/can sense things like heartbeats or other bodily functions.
-First and foremost, while Hiei has a heart, it doesn't beat. Why is it there if it doesn't have a purpose? I don't even know. Instead, demons have an energy core that pulses, pumping blood throughout the body (apparently. how do I shot demon physiology).
-Second, Hiei's Jagan--that third eye that gives him psychic powers--is
a) semi-sentient and
b) surgically implanted, not natural, though it is definitely connected directly to his brain.
What this means for you is that if your character can sense...you know, the presence of beings, they might pick up both the dragon of the darkness flame and the Jagan. Hiei has a pretty tight control on it, but it's there.