Ah, I will be conspicuous and self-pimp a post "Bride of Peladon" story: Walks Through Walls. It's Erimem and Six, written for the 2009 Sixathon, so it has mild allusions to some of the Sixth Doctor audios (The Holy Terror, The Wormery, some Six and Charley stuff). It's about Six getting Erimem a new cat, but really it's about Erimem and the Doctor, and why she left and why he doesn't (usually) look back.