I'm a half demon. My father was an incubus, and the demonic blood makes me unstable. In my world, sometimes this would mean I went on a rampage, following my demonic side's whims and wishes. This seems to happen less often here than it did at home.

Right now, we think it's a lunar cycle. Every new moon, I turn into a psychotic, blood-thirsty bitch of a succubus. there's no physical change, just my demonic urges bubbling up.