Basically, I was in an RP like this quite some time ago. Of course, I'll have my modifications. The plot revolves around the demon(ess) trying to cope with strange feelings for a human. There are four types or elements of demon, the Sylph, air-based, the Salamanders, fire-based, the Undines, water-based, and Gnomes, earth-based. I'm only using the names of these elemental beings from the works of Paracelsus, not any traits that may exist thereof. The demon/ess can have more or less any trait or traits the player feels appropriate, as long as they can be related to the element somehow. The demon will need to avoid their 'negative,' (Fire vs. Water, Air vs. Earth) and are empowered by their 'positive,' objects or environments pertaining to their own element, (Salamander is empowered by standing in/near fire, Gnome by consuming the earth, Undine by being in water, Sylph by strong winds)
I'd prefer to actually start 1x1 thread rather than PMs, so if you're a PM-only 1x1 RPer, don't apply.