Now I've been reading the Norse legends for years.  (Way before I first saw
my first copy of OMG).  Anyways I've always wondered where certain
characters (read: monsters) went from the mythology.  Here's my play on one
of them.

[A little history/mythology lesson here (hehehe :)). Loki marryed an _UGLY_
giantess (that's a bad thing, marrying a giantess I mean) and had three
children: the wolf, Fenris; Hel, a blue & flesh colored creature; and
Io(double dots above the 'o')rmungandr a venomous serpent.]

I'm going to talk about Iormungrandr, Aka The Midgard Serpent.  The Midgard
Serpent, when born, was thrown into the sea and grew to encircle the world
(Midgard) by swallowing his tail.

[plot starts here, time: just after Skuld's arrival on earth]
Up in Asgurd (read: heaven) SOMEONE accedenly opens an MS-Window (I know,
but it fits with the computer/Yggdrasill thing) releasing some poison (read:
virus) into the world tree.  Things start to go wrong down on earth as a
result of the virus, the Ultimate Forse no longer binds Beldandy and Keiichi
(sp?).  Urd trys to keep
them together (not that she _really_ needs to and gets her usual results)
while trying to help Skuld figure out how to stop the virus (while dealing
with a new breed of bug).

Well there you go.
Maybe someone night even write this.  :)
I haven't seen enough of the OVAs or read enough of the manga to really
write this.  So please, help yourself.