I'm not a big fan of SI fanfics (personally I think most of them are
poorly done), but just a few weeks ago I got an idea for one. My
question is: in a self-insertion fic, has anyone ever cast themselves
as the bad guy/antagonist, and not as a living power battery/new-and-
most-powerful team member/love interest?

There are a few.  "Youma Blues" had an SI character who found himself stuck in
the Sailor Moon universe as a low-ranking youma.  Lara Bartram once wrote a
fic where her avatar dropped into the Ranma universe for the sole purpose of
mucking up everyone's lives, using only her wit and her knowledge of the 
series. (She's since written several sequels showing what's happened to the 
people there after she left.)  Ed Becerra's simply incredible "Legion's Quest" 
centers around a cosmically-powerful SI who still gets stuck with annoying or
embarassing situations and sad-sack problems.  Bert Van Vliet's avatar in the
still-unfinished-but-still-being-written Bubblegum Zone actually has a tally
page on the web for how many injuries (and how severe) he's taken in the course
of the story; and his only advantage in the BGC universe -- his knowledge of the
series -- has vanished due to timeline divergence.  

I'm sure others here on the ML can point you at more.  Not every SI is a 
Twister, as fun as he is...

-- Bob

-- 
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Robert M. Schroeck          || "When in trouble or in doubt,
rms@eclipse.net             ||     Run in circles, scream and shout."
http://www.eclipse.net/~rms || I have no mouse and I must scream.
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