I just realized that none of my original plot prompts are medieval or fantasy in nature (besides the quasi-Gothic horror one), but you should still read my IntChk anyway and see if you like anything. Link. Our philosophies on writing line up really well so I bet we could work something out.
Mine is Vikings and the Dark Ages. If you want to combine the two and have some sort of Varangian Guard deal, let me know. Still interested in any other ideas though.