For some reason, there are many fics based on "Witness". Perhaps it's for the reasons mentioned above, where the L&C relationship does take a step forward. Some of my personal favorites are listed below.

"Teamwork" by the inimitable Nan Smith - always compulsively readable.

"Snowbound" by Deadly Chakram doesn't have a huge connection to the episode, but it's great fun! Don't miss this fine fic by one of the new fine authors on the site.

Another one where the episode connection is a little shaky, but still a good fic: "Finding Christmas Spirit" by the prolific Wendy Richards.

Matrix tells the story of what would have happened had there been an inadvertent revelation for Lois in "Witnessed" . Another author not to miss.

And Mozartmaid follows with the "Lois Revelation" theme in "Night Witness" . I've always wondered what might happen if Lois "found out" earlier, and MM tells me here.