Thank you so much for volunteering to write in one of the fandoms I requested!
First of all, I hope you will write something you enjoy writing. And Optional Details are Optional! So if none of what I've suggested is helpful, please go in your own direction!
In general:
Things I love: Humor, banter, fond looks, characters being in denial, wacky hijinks, passing the Bechdel test
Things I don't love as much: Despair with no humor or hope to lighten it, PWP (for Yuletide at least), character bashing, humiliation
While I've specified my especial favorites in each of my requests, I really do love all of the characters in each of these source materials!
More specifically:
Shades of Grey; Jasper Fforde
Eddie Russet, Jane Grey
I love the universe in this book, especially the mystery that Eddie and Jane are beginning to uncover. I would love to read about them dealing with the events at the end of the book, or perhaps learning more about The Something That Happened.
Getting to spend more time with these characters would be delightful! I don't really have anything to add to this request.
Red, (2010)
Frank Moses, Sarah Ross
I love Frank/Sarah, but a mission-style plot that was more gen would be great too! I'd love to read about what happened in Moldova, or how Frank and Sarah originally started talking/got to be friends. Or maybe Victoria and Sarah talking about the best ways to kill people. If you lean more towards gen, the more characters the better!
Really, there is no story you could write involving Frank and Sarah that I would not love. Seriously. I love them a lot. If you do involve the other characters, Marvin and Victoria are my favorites, but really, I love everyone!
Newsflesh Series; Mira Grant
Georgia Mason
I will love any story about Georgia! I think Georgia/Shaun is pretty interesting, but if that doesn't grab you then gen is great too. I'd love to read more about her family interactions, in particular. The more zombies the better!
One small thing: I know it's a bit of a plot point in the book, but animal harm is very much not my favorite thing, so if you can avoid it that would be awesome!
Oxford Time Travel Universe; Connie Willis
Polly Churchill
Basically, I want to spend more time in this universe. Polly is my favorite character but I love Eileen and Mike as well, and of course Colin and Mr. Dunworthy, so include anyone you'd like! I would love to read a pre-book story about how Polly decided she wanted to be a historian, or how she met Colin, or a missing scene from Blackout or All Clear, or a story about what happens after All Clear. Really, anything!
I tried to be vague in case you haven't read All Clear yet, and if you haven't, a story set during Blackout would be great! But I did really love the ending of All Clear if you have read it, so feel free to run with that!