Thanks to icedark_elf's fic "Confused", thoughts of demony!Zack and demony!Cloud have taken up residence in my brain and stubbornly refuse to go away, damn it!
EDIT: I forgot to mention that icedark_elf's fic "Ravens" also provided fodder for the plotbunnies, so she's DOUBLY to blame for this insanity! :P
Evil-OT4? How can that be, you ask? ^_-
Well, here's an example of one of the evil-OT4-plotbunnies now happily breeding inside my heads....
Let's say that Sephiroth goes crazy at Nibelheim, just as in the game. However, during the fight in the Nibel Reactor, something dire, feral, and parasitic (but non-Jenova) gets released and infects both Zack and Cloud. Sephiroth doesn't get infected because he gets thrown (or jumps) into the Lifestream. Let's assume that Hojo conveniently doesn't know about said parasites. Zack and Cloud get experimented on by Hojo as per the game, but unknown to everyone, the parasites, while dormant, are busily incubating inside them. Eventually, Zack and Cloud escape, but after their escape, the parasites become active and they transform into incredibly powerful psychotic variants of themselves.
So now we have psycho!feral!Zack with gorgeous black wings and psycho!feral!Cloud with equally gorgeous gold wings, who are: (1) pissed off at the world in general and Shinra (and Hojo) in particular; and (2) are looking for their other two lost mates (i.e., Sephiroth and Aeris), whom they intend to infect so they can become one big happy psycho!feral!OT4 pack preying on puny humanity. Whee!
One possible result of all this is that Aeris somehow finds out about what's happened to Zack and Cloud and wants to save both them and humanity. She somehow hooks up with AVALANCHE (obviously sans Cloud) and it all becomes a desperate race to find and awaken Sephiroth before Zack and Cloud can find and bring him over to the 'dark side'. Another interesting consequence is that AVALANCHE and Shinra could end up joining forces in order to protect Aeris and keep both her and Sephiroth out of the grasp of psycho!feral!Zack and psycho!feral!Cloud.
Hell, it's even possible that Jenova joins forces with AVALANCHE and Shinra (Jenova, because this new parasite is a dangerous competitor who's trying to steal her 'children' -- Sephiroth, Zack, and Cloud -- away from her), although Jenova would definitely be a rather untrustworthy ally.
Of course, this assumes that Aeris wants to stop Zack and Cloud. But what if she doesn't? What if she just wants to be with her loved ones, regardless of the circumstances. In which case, Shinra and/or AVALANCHE will be trying to keep her from joining or assisting Zack and Cloud.
The same question applies to Sephiroth. If/when he wakes up, would he want to stop Zack and Cloud (either of his own free will or on Jenova's prodding), or would he want to join them?
Or if we want the game events to take place as normal, we can have the parasites dormant until after the Meteor incident, in which case, psycho!feral!Zack appears and tracks down Cloud, who either transforms immediately or gradually (wonderful chance for some Cloud-torture here!). In which case, psycho!Zack (with or without Cloud's help) will be trying to pry Sephiroth and Aeris out of the Lifestream....
Damn it!!! Just look at those evil-evil-OT4-plotbunnies multiplying!
Ummmm... reality check here. Has anyone heard or read of a plot like this? ::massive sweatdrop:: Because if they have, let me know and I'll stuff these guys away in a drawer somewhere.
On the other hand.... wouldn't it be great if psycho!Zack and psycho!Cloud succeeded? ^_^ Then we'd have a gorgeous, predatory OT4 pack with:
(1) Zack, with black feathered wings and a lupine alter-form
(2) Cloud, with gold feathered wings and an avian alter-form
(3) Sephiroth, with silver feathered wings and a feline alter-form
(4) last, but certainly not least, Aeris, their beloved bitch queen! (EDIT: perhaps she gets a flora-based alter-form, an idea sparked by ladynero's crackfic.)
Let humanity and the Planet quake and shiver in terror!
::slithers away, cackling madly::
MASSIVE EDIT / ADDITION: Spawned by forgottenlover's and mimi_sardinia's comments.
I had been assuming that this parasite was just some unknown alien critter. But what if it wasn't? What if this parasite is Cetra-based? This would be a good explanation for its presence in Nibelheim and Hojo's/Shinra's ignorance of its existance. Also, it provides a perfect explanation for its seductive pull on Aeris and others. ::gleeglee::
What if it was a weapon created by the Cetra to battle Jenova, but for whatever reasons, was never deployed or activated?
Or better yet, what if it was the Cetra's dirty ancestral secret, their skeleton in the closet? What if long, long time ago, the Cetra were predators and/or parasites just like Jenova, infecting and preying on worlds. But somewhere along the way, the Cetra turned their backs on their bloody past and started to nuture worlds, perhaps to make up for their past sins. But unknown to the Cetra, they hadn't escaped their dirty secret -- it had merely gone dormant and they were unknowingly carrying it with them wherever they went.
But now this ancestral or true Cetra parasite (or form) is now active and is reverting to its normal predatory habits. Here's a nice tasty planet, only there's this annoying competitor (Jenova) lurking around. And even worse, this competitor has the NERVE to infect some of its own. Well, the Centra parasite isn't about to let that go on, which would explain why Zack (and Cloud) are hunting for Aeris. Not just because she's their mate, or that she's a breeder, but she can help cleanse that foul Jenova-stuff from her mates (or subvert it to serve Cetra interests). ^___^
Sooo.... what would happen if others (especially AVALANCHE) got infected?
Vincent - doesn't really need any changes. In fact, infection by the Cetra parasite is a perfect explanation for his transformations and powers ::beams:: Only no one realizes it... until it's too late.
Cid - becomes a winged draconic creature, of course! Even better if he can becomes a sky-space dragon. Bahamut Zero, anyone?
Yuffie - becomes a serpent-like draconic creature (like Leviathan). Alternatively, something that reflects her ninja abilities, perhaps some sort of shadow creature?
Reeve - remaining superficially human in appearance, but some sort of cyberpathic entity, controlling technology with will and thoughts alone. On the other hand, he can now switch freely between different bodies and/or inhabit multiple bodies simultaneously.
Nanaki - instead of developing demonic/beast traits, he develops humanoid traits (e.g., becoming bipedal, opposible hands, etc.)
Rufus - not sure, but I picture him
Actually, I'm inclined to have Tifa (and Barret) remain uninfected and human. Yes, I'm evil to her that way, making her watch and futilely struggle as all her teammates get converted. It would be no fun if no one was around to angst about it. ::cackle::
Really, I'm so bad. ::heads droop in mock-shame::
And yet MORE additions: Again spawned by mimi_sardinia, who's being particularly evil to me.
mimi_sardinia proposed an interesting variation of the ancestral Cetra virus theory here. What if there were two strains of this ancestral Cetra virus -- a pacifistic, nurturing variant strain (embodied by Aeris) and an aggressive, predatory 'true' strain (infecting Zack, Cloud, Vincent, etc.)? The bearers of the strains are still drawn to each other, but Aeris would be understandably disturbed by this 'dark/feral' aspect that Zack and Cloud are showing.
Also, I realized that this particular plotbunny (or plot chocobo) can work AFTER the events of "Advent Children". It's possible that the elimination of the Geostigma helps to trigger the awakening of the ancestral Cetra virus/parasite. Due to his prior infection, Zack's spirit gets pulled out of the Lifestream, back into his infected body. However, Aeris's original body is somewhere in the waters around the City of Ancients, and Sephiroth's body is who-knows-where.
Wouldn't it be interesting if Red XIII's long-lived race has some critical information about this previously unknown feral-Cetra strain? ::eyebrow waggle::
Okay, I'm giving this plotbunny the working name of "Feral-verse", at least for now. ^_^;;