In the mythologies of many cultures around the world, twins make frequent appearances. They appear both fortuitous in some and ominous in others. Twins in mythology are often cast as two-halves of the same whole, sharing a bond deeper than those of other ordinary siblings, or facing fierce rivalry. Sometimes twins can represent some "other" aspect of the "self"- either a doppelganger or a shadow. Often in mythology the twin is evil, or the other one may be human and the other is semi-divine.