Does there need to be a ficathon? A challenge? A fic exchange? Let's see what the interest level is.
I'd write for a Buffy/Giles ficathon.
I'd eagerly await the opportunity to read the results.
Ficathon formats I like are:
Traditional fic exchange, with assignments.
A fixed set of prompts I can select from.
A single challenge that all stories must respond to.
"Buffy/Giles" is enough of a prompt.
Another idea that I will tell you about in a comment.
The pairing is properly written as:
A disgusting portmanteau name, like "Biles" or "Guffy".
That last option wasn't biased at all, now, was it. Sheesh.
If there's enough interest, I'll fire up the ficathon machinery when I return from vacation. Heck, if there's a lot of interest, I'll start the machinery moving remotely. Will have my Macbook with me in sunny, warm England.
ETA: I'm doing it! Signups are now open!