*Spoilers for Third Transmission*
I was browsing the Fanfiction.net site and came up with only one Six of Hearts Fanfic on there, this one. I really like it, and a brilliant writer's credit for Lillith Skywalker. It's supposed to be a new ending to Third Transmission... based after the end of Third Transmission.
Angelic Voices, An Agent Six of Hearts Fanfic.