Wivern is a creature borne from and who thrives on the despair of others. Its origins are not known, but it has appeared and reappeared unpredictably throughout the last several hundred years.

Parasitic and possessive, Wivern seeks out and gradually inhabits the body of a host in great personal distress. This is, of course, a horrific experience for the host, who usually despairs more as a result, which in turn gives Wivern more strength. Wivern influences its host to make decisions and take actions which exact the most emotional toll to give itself more power.

Eventually, Wivern is in full control of its host's body, though the host's mind remains fully conscious and aware of all its actions. At this point, Wivern is able to transform into its true form, a six-winged, many-eyed beast, and cause despair on a grander scale, generally in the form of mass destruction. It's not uncommon for Wivern to keep its host's family and loved ones alive to maximise ongoing emotional torture.

It's presumed that Wivern will die if Wivern's host dies while its in possession, but too slow a death would allow for Wivern's escape into a nearby host who is despairing sufficiently. This has allowed Wivern's continued survival throughout the years, as it is usually a loved one of the host who must kill the host, and Wivern would thus escape into this person as its host dies.