The Star Trek fandom has extremely specific guidelines for how it labels stories, which was very helpful when sorting through the daily listings of alt.startrek.creative. If I'm remembering correctly, non-romantic or sexual interaction used an ampersand between the names. It was fairly intuitive and allowed for very specific description of stories (K/S, K&Sc, U&S to make up a random example of what a story could look like). I think that'd work here.