We've had conversations on this one in the past and I don't think we've ever reached a concensus yet.
I have a personal preference for Lois' - not out of any sense of logic or grammar rules, but simply because I arbitrarily think that Lois's looks dashed clumsy.
When I'm beta-reading or GEing for the Archive, I tend to just let it be down to the individual choice of the author. I did flirt with trying to insist on Lois's for a brief period and did try making myself use it too, but in the end thought, what the heck, since no one seems to be able to pin it down one way or another, it may as well be down to the individual.
I'll definitely go with other posters - consistency is the main thing, either way.
LabRat
