In an alternate universe, Lex Luthor reformed and married Lois Lane. Sadly, their son, Larry, grew up to be a notorious criminal, Black Luthor. However, he also reformed eventually, and married Joan, the daughter of Superman and Lana Lang.
Note:This was an 'imaginary story'. In Crisis on Infinite Earths: The Compendium, it was retconned as having happened on Earth Thirty-Four.