As I've said before, it's sort of difficult to nail down the details of how John and Elly got together; this is, of course, because Lynn refuses to tell a consistent story of how the two of them met up, how their relationship grew, when Elly put her academic career on hold and how many years in that Mike came into the picture. This inability of hers to tell the same story twice, as well as her suggestion that we write it as we see fit, has raised an interesting possibility in aprilp_katje's mind; John is Elly's second husband and Mike's step-father. This is because John and Elly's refusal to tell their kids a consistent version of the past looks very much like their trying to hide something from them. The signs are sort of obvious; Elly and John's courtship seems to have been the same business-like deal we saw in the Settlepocalypse, the two of them treat Mike like he's an unwelcome reminder of an unpleasant subject and they dote on the child they did have together. If that is the case, it sort of means that Liz will end up marrying a man like her mom and being her dad.