America loves TV about polygamy. After four years of the scintillating fiction of "Big Love," we were ready for fact. Or, at least, the reality-TV version of it. TLC’s series "Sister Wives" finally arrived in 2010, and the second season has just begun, as "Big Love" concludes this weekend. Like an elephant with a friendly bird to eat flies off of its back, the two shows have formed a sort of symbiosis.

Fact and fiction intertwine: "Sister Wives" shows you the real-life versions of the characters. "Big Love" shows you what they might look like in bed. The excitement of "Big Love" relied on our faith in the [...]