Let me begin by thanking you for offering one of my fandoms. I'm sure I'm going to love whatever you write, but since you're probably looking for some ideas and guidance, I'll try to provide you with some suggestions. Note that I've requested many of these things before, and have received some great stories, but I'm of the opinion there can always be more. I love seeing alternate takes on the same basic idea. (Note that I'm requesting fanfic for all fandoms.)
First, some general wants/do not wants.
Wants: (Things I especially like, if they happen to fit in with the story you want to tell.)
Snarky characters, physical or mental h/c, PWP, gen, character studies, adventure, women or other characters who are usually in need of rescue turning the tables and being the hero. Humor, up to and including crack – which would be more than appropriate for many of these fandoms. Horror. Note that I'm fine with drunken dub-con/aliens made them do it/sex pollen/the like. For this exchange, I'm also okay with gore, violence and secondary character deaths.
Do not wants: (Things that I'm either not interested in for this exchange or that simply don't work for me with the fandoms and characters I've requested.)
Main (requested) character death, non-con, a/b/o, genderswap, male or female pregnancy, kid fic, curtain fic, coffee shop/band/etc type A/Us, most kinks other than some mild bondage.
Now for specific fandoms – in no particular order:
Geico Kraken commercial – available here:https://www.youtube.com/watch?v=SaJWYjWt
This commercial raises so many questions. Why is there a Kraken in the water hazard, and how did it get there? Does that golfer really think his 9 iron is going to save him? Are the announcers going to keep whispering? Crack would be great.
The Writer Automation - available here:http://www.chonday.com/Videos/the-writer-a
It might be the music, but this gives me the creeps. Maybe the automation starts writing things on its own. Maybe it starts predicting people's deaths, or reading minds? Would love a horror take on this.
AT&T Polite Dinner - available here:https://www.youtube.com/watch?v=LVDWfuiD
These people are just too happy – it's not normal. I can't help but think there's something else going on – maybe they've been replaced by aliens? Or I can picture a basement full of dead bodies that they've killed as stress relief? Pod people? Any sort of horror would be great.
The Undeading - available here:https://www.youtube.com/watch?v=ApmPQDAz
Zombies that give you CPR to bring you back to life before they eat you? So many unanswered questions. How did the outbreak happen? The jets going overhead – are they bombing the cities? It seems the zombies retain some of their “human” knowledge? Go anywhere with this.
SCP Foundation - available here:http://www.scp-wiki.net/scp-978
SCP-978 is a camera that takes photos which show the true desires of the photographed subject. I've gotten a couple great stories, but the idea still fascinates me, and I'd love to see other takes on this. Perhaps the camera could take photos of the characters from another fandom? (Anything I've written in or asked for in an exchange, or just ask if I'm familiar with your favorite fandom.) Go as dark or as light and cracky as you'd like with this.
The Big Bang TheorySheldon
Sheldon is my favorite character, and I ship him with both Penny and Amy if you want to go that route. A few different ideas – Sheldon invents a time machine and things go very wrong? Something shippy – maybe something that starts as a scientific experiment? Or, if the idea inspires you – I've always wondered if Sheldon's aversion to touching and his demands about people staying out of his room could suggest that at some time (college? Or by his drunken father?) he was physically or sexually abused? (Consider this an exception to my non-con and kink DNWs – go as dark as you'd like.) Whatever you write, feel free to add others from the show as desired.
(Late edit. I just discovered the 50 Nerds of Grey twitter accout here: https://twitter.com/50NerdsofGrey - if you would like to use ANY of those tweets as a prompt, GO FOR IT!)
What if Keller came up with a treatment to make the Wraith human, but it didn't quite work – instead of life force, the Wraith started feeding on human blood? (That could still be a good thing, if Todd could find willing donors.) If you're interested in writing actual Halloween fic, perhaps Todd could be introduced to the concept of Trick or Treat? If you want to write pairing fic, I'd prefer you match Todd with John or Rodney rather than Jennifer.
For once, one of Castle's wild theories turns out to be true. Aliens, zombies, vampires, Godzilla? The crazier the better. Either crack or horror, or a combination of both. Add other characters as needed.
AirwolfMichael Coldsmith Briggs III
I ship Michael with either Caitlin or Marella if you'd like to go that route. If you're looking for something darker, in the course of three years, Michael has been blown up, brainwashed and tortured. Surely that's messed up his head at least a little? Nightmares, PTSD? Or maybe Michael gets to save Hawke for a change.
Anyhow.... Hopefully I've given you some ideas, or perhaps you have some of your own. I'm sure that if you write something that you enjoy, I'll like it, too, so have fun and don't stress!