In The Unborn, written and directed by David S. Goyer (probably best known for having co-written Batman Begins, but also the guy who wrote Blade, wrote/directed Blade: Trinity and created Blade: The Series), Odette Yustman's character becomes convinced that she's being haunted by the ghost of her twin brother, who died in the womb, after her left eye starts to change color from brown to blue. Further research reveals that the "ghost" is actually a dybbuk, a demon from Talmudic mythology which briefly entered the body of her great-uncle after he was killed during Mengele's twin experiments at Auschwitz. Recognizing that what had "come back" very definitely wasn't her brother, Yustman's grandmother killed him again, thus incurring the dybbuk's wrath; it's particularly attracted to Yustman's bloodline because twinship runs rampant in it, and mirrors are the easiest doorways through which a dybbuk can enter the fleshly universe ("...what is a twin but another sort of mirror?" Grandma remarks, in perhaps the film's best line).