The Knight of the Sword is a moderately obscure bit of Arthuriana featuring the redoubtable Sir Gawain. It has two main episodes, the Perilous Bed and the Maiden and the Hounds. (Both episodes are found with different protagonists in other works; it's sort of early TV Tropes.) Three years pass between the end of the Perilous Bed and start of the Maiden and the Hounds, and it looked like a perfect spot to insert a "new fragment."
Except... this is a moderately obscure work. I'd have a decent chance of being able to start something off with "Not long after Arthur pulled Excalibur from the stone" and have everyone know what I was talking about. "Not long after Sir Gawain married the maiden of the Perilous Bed"? Not so much.
I think I have two options at this late date:
1) Expand on the "Branwen seeks a cure" idea I used to sell this contest in the first place.
2) Write a 100-ish line version of the Perilous Bed episode (the original runs hundreds of lines). It's a bit bawdy, which makes it a more appealing performance piece than the Branwen, unless I come up with some interesting ideas for that one.