Worst-case scenario for a sex pollen type scenario: it's not a pollen, but a virus which mutates very rapidly, so it can be caught again and no cure can be developed. And it gets transmitted as easily as the common cold, maybe has an incubation or contagious but no symptoms period. Obviously would require lots of research about disease transmission.

Back in the day, Methos was Egeria's host and the catalyst for her change of heart. Post-Horsemen, even though that means changing the date that they rode, so he knows the temptation and appeal of power and has gotten over it. So they Tok'Ra around for a while, then get caught, Methos "killed", Egeria imprisoned. Fast forward to the present; for some reason, Methos is with SG-1 when they find Egeria.

Dexter Peggy Sue: Dexter wakes up back as a child/teenager (before Harry died), with all of his experience with life and killing. Not to mention years of seeing and getting advice from hallucination!Harry, which doubtless does not match up entirely with what real!Harry would say. And experience pretending to be a normal person. And, you know, the fact that killing animals won't cut it anymore.

In the myth of Er, Odysseus decides to become reincarnated as an ordinary person. So...what if that ordinary person is John Watson?

So, one day God says to Joan, "I need you to change your name/get a really good fake ID and go to Miami." The name on her ID is Lumen Pierce.

Methos was in Grantville when the ring of fire happened, either with or without the others (this could be done with almost any immortal, but if I did it I'd do it with Methos; Duncan would be less interesting because in 1632 he was still a baby Immortal...okay, that might be interesting, too). And he knows that younger!Methos is going to come to Grantville, as well as probably a shitload of other immortals, because it's interesting and completely new. But what's he going to do, leave the only real civilization that exists?

Sometime before he meets John, one of sherlock's experiments goes horribly wrong and now he's a zombie. Those body parts? Not (just) for experiments. And he doesn't eat a lot of normal food because it does nothing for him. Nobody knows except Mycroft. But then, somebody finds evidence that he eats the body parts.

Theseus runs around, defeating bad guys by turning their own tricks back on them. So does Jarod. So...what if Theseus was a Pretender?

So, I just read a very short X-Men/Highlander crossover where Joe was a mutant. Which would be really interesting to explore more in-depth.

Admittance to Hogwarts is technically based not on age, but on some whacky magic milestone. It's just that, because its students have all been human, that milestone happens at 11 for all of them. For Immortals it happens after 5000+ years. Methos gets an invitation to Hogwarts, and decides to go because it's something new.

The Marauders' Map is a horcrux of its creators.

The Leverage crew all got killed in the pilot, but they all stuck around as ghosts and don't realize that they're dead. And they're so awesome at acting that they fool everybody, even though normally it takes decades for ghosts to figure out how to affect the physical world or be visible.

And then the Winchesters figure it out.

When Kal-El landed on Earth as a baby, the Kents somehow got Kryptonian powers and the instinctual knowledge of how to use them. Although it's interesting to contemplate how things might be different in the big picture when his powers aren't a unique thing, but rather a family thing, I'm more interested in a random domestic scene where they all...heat up their tea with laser vision, or something, extremely casual about it

Variation on an earlier idea:

After the most recent fun with thieves disguised as terrorists (which could be any of the movies! :D), John McClane gets a new partner. He keeps getting stuck with the undesirables because nobody else can handle his crazy, so it's not really a surprise that he gets stuck with the new guy...who just moved to New York from the UK. How much of the city will be destroyed in the name of saving lives before John McClane and Harry Potter get split up?

Starfleet Academy (well, technically, everybody, but only SFA or possibly just the students remembers it) gets caught in a time loop before all the craziness. Things, um, get a little bit crazy. Especially since it's one of their emergency simulation days and Kirk's in charge.

I've never seen Joan of Arcadia, but I'm pretty sure that she was a nice and normal girl before god started talking to her. What if she wasn't? What if she was more like Dexter, only faking being normal, and holding off on her darker impulses as long as she could because if she could love anybody, she'd love her family?

Somehow, Luke and Leia ended up getting raised by Han (er, might need some age juggling, there) and Chewbacca. And then, they give Ben Kenobi a ride...

Harry Potter isn't the only new student at Hogwarts who was left with relatives as a baby--Luke Skywalker was, too. In the Star Wars universe, not ours; Hogwarts serves only Tatooine.

One of the Highlander characters on Pandora or as a red shirt, getting killed over and over and over again but with no place else to go even if they desert or whatever. Comedy.

Terry being Bruce Wayne's assistant is just a cover story, but this is Bruce Wayne we're talking about; do you really think he doesn't expect Terry to actually do what he's expected to do? Yeah, Bruce covers for him sometimes, does the job instead when nobody else can see, but if he creates the cover story of grooming Terry to take over then he's damn well expecting Terry to learn how to do so. So Terry has to go to meetings and stuff, and take on ever-increasing responsibilities there as well.

I read this summary of a Criminal Minds/Big Bang Theory crossover: "Gideon recruited a different genius to the BAU, and nobody is particularly happy about it." I don't know BBT, but there are so many interesting geniuses that could have been (possibly minus that last part). Personally, I favor Shawn Spencer (who could be interesting in the changes to him from working that kind of case, as well as differences from canon--AU, or preseries with a later 'BAU comes to Santa Barbara' plot). But, since I haven't watched Criminal Minds...*shrugs*

The more you practice magic, the more you have to use it. So...there's somebody who has to use magic. Normally it's not a problem; they just use it for little things throughout the day, most of them not anything that would be noticed even by somebody looking right at them. But then there's something tha prevents them from doing magic: a curse, or they're trapped in a warded house, or something. They're not alone. And because they can't use magic, it builds up in them. The first side effects are small, easily ignored, usually a sign to use magic. Later, they start acting like they're on drugs. If it goes on long enough they'll die.

Sentinels are (and perhaps always have been) known to the public. John Watson awakened as a Sentinel while he was in the Army, where they take a very military approach to things (which is more than a little bit different from things for civilians); he's never experienced life as a civilian Sentinel until he's discharged. His therapist thinks his limp is because he's so traumatized by the death of his Guide. John never told anybody that he never really saw the point of a Guide, since he was so new to being a Sentinel; all of the Sentinel experts insisted that all Sentinels needed a Guide. Just because his Guide never really seemed to do a thing for him (not that the guy was incompetent or anything; he just felt the same with or without the Guide) didn't mean John knew everything. Maybe it was just a subtler effect than he'd been told that it was; after all, he'd never really had any problem with zoning, but maybe that was because he got hooked up with the Guide right away. And certainly, after he returned to London he started to have problems with zoning.

Sherlock refuses to believe that Sentinels need Guides, and from the first day sets out to prove it to John. (Either he's just a normal person or he's a Sentinel who couldn't take a normal job if he wanted to because he doesn't have a Guide...I think I prefer the normal person).

Once John is in "London is a battlefield" mode, his zoning problems disappear completely. Most people don't realize that he's a Sentinel, because he doesn't do obviously Sentinel things like zoning or having a Guide going everywhere with him. Lestrade and Co. realize, because at the first crime scene (and all subsequent ones) Sherlock has no problem ordering him to use his senses. People who do know keep taking him and Sherlock for a Sentinel/Guide pair, to which they keep going "um, no"; Sherlock doesn't have the Guide genes at all, and even if he did he'd be the worst Guide ever.

John can't get a job (at least as a doctor...nobody would care if he was trying to become a janitor or something, but there's liability involved if he zones out during something important) unless he has a Guide. John really doesn't want to put Sherlock down (and there's nobody else he can put down), but if he doesn't he won't be able to get a job. He gets really irritated at that and other ways that civilian Sentinels are treated; he has his senses under control, he doesn't need to be treated like he's going to break if he does things like a normal person. Sherlock treats him like a normal person, which is awesome even if Sherlock's usual way of treating normal people leaves something to be desired.

Sherlock is NOT John's Guide, and he's totally right about (some) Sentinels not needing a Guide.

Methos moves on to his next life, deciding he wants to be a tailor again, and starts up his business somewhere close to some community of mutants. Slowly word gets out to the mutant community that he's good, professional, cheap, and discreet. On the side he teaches a few mutants how to make alterations that aren't covered in sewing books. And then, without warning, he disappears, and the next time anybody sees him he's "Sgt. Lyman".

Harry Potter was raised (with great difficulty) by dragons. No, not around dragons, or by dragon keepers. By dragons. Who are sentient, intelligent, and baffled by humans, but know that, as Harry is a human, they need to raise him in a humanish way: clothes (before he can dress himself, it's very difficult for them, and since he doesn't see other humans except from a distance, his clothes are weird), teaching him human skills (they're not sure which ones are important, so they teach what they've observed and whatever they have books about, and some of it's inaccurate or rare, and they miss some major things), etc. And then, when he turns 11, he goes to Hogwarts.

Okay, so I just read In the Dark (http://www.fanfiction.net/s/6373793/8/Toil_and_trouble), and now I kind of want to write something along those lines but extended--starting back in the HP'verse, year 4 when Harry and the horntail met, show how it went AU, and then follow it into the Temeraire verse. But the research...!

Gryffindor!Snape

Before they go through 7 years of being stereotyped for their House while attending Hogwarts, witches/wizards are a lot more balanced. Snape was no exception (as a character who approximates a normal human, you can see elements of all four houses in him even in canon). He wanted to be in Slytherin like his mom, and didn't want to be anywhere near Potter & Black after meeting them before getting to Hogwarts, but the Hat disregarded that and stuck him in Gryffindor anyway, where he was even less able to escape from his tormentors than in canon--thus, he still gets pushed towards joining the DEs, because the smarter, more Slytherin ones realize that they can use him--he's already inventing spells and potions while he's still in school, after all.

But how does being a Gryffindor change him? On the one hand, changing Houses is a pretty big thing; on the other, he's pretty much dead set against having anything in common with the Marauders.

Simba grew up, ruled the Pride, yada yada...and then later he somehow became Aslan. Support:

• Simba and Aslan are both of the Jesus archetype
• both have a noncorporeal father that they talk to
• lions
• both rule over assorted animals, not just lions

The apocalypse comes, and it's even worse than a lot of people are expecting because, hey, in the real world all of the fruit and vegetable plants they sell (including, or perhaps especially, those sold to commercial farmers) are designed to be sterile--as in, after the crop that's currently in the ground gets harvested, if there isn't any more seed to be bought then we're not going to have anything to live off of other than domestic animals and whatever we can find out in the wild.

Wizards cosplaying muggles.