Three words: epic relationship story. I absolutely adore the really long stories that somehow involve Lois and Clark getting together, like...oh...Accidental Husband or First Comes Marriage, to name a couple.
I like elseworlds, too (especially relationship elseworlds :p )...Star Player, Star Reporter and...hm...OH! Lost and Found. Wow, I have to read that tonight. It's one of my favorites.
