What's to say? Hell's not a very pleasant place! Still people can't help but get involved with that plane! Summoning incubi and succubi, if you're just plain unlucky, you might end up summoning, Iris.
Iris used to be like any other incubus, but after a certain incident he's picked up a very bad habit. During that incident, frustrated and terribly starved after a long dry spell of no summonings, he ended up viciously devouring the woman who called him. It was that time that, eating was just as pleasant or even more so than normal "feeding". Curious about this new thrill, after that time many of his other summoners had disappeared. With hellish magic at his disposal, he can't help but want to spice things up a little.
Still he can be rather pleasant if you catch him when he's not in the mood to eat but to "feed". Successfully befriend him and you'll find he's cheerful, upbeat and rather playful. If he really grows to like someone he tends to turn affectionate and needy for attention and very quickly into territorial or possessive. If he feels his current object of affections is threatened...you can say he practices "defensive eating" or worse. He's still a demon, there are many acts he's not above to get what he wants.
Lately though, eating a few magical humans has given him some interesting abilities, such as being able to walk on the surface without a summoner.
*Note, Iris's abilities are not set in stone and vary based on scene from scene. He's essentially as powerful as he needs to be