This one really affects me personally as my sons current mission is apparently to demonize me to Lil, to turn me into the classic wicked step parent.
I would be prepared for him trying to "split" you two.
That could take several forms. He could go to one of you and try to rat on or set up the other.
"Dad is hard and hostile to me, Mom. This is really working against my succeeding. If
I could only have a chance to really put this into place, without his negativity. I think working in prison all those years really distorted his thinking. Can we try, Mom, to work this out?"
Or, the flipside: "You and I are reasonable and rational Dad. We think alike on this issue. Without reacting and losing focus. But Mom lets her feelings get in the way every, single time. I know we can work something out, Dad."
Here is a brief definition of splitting from Wikipedia:
"Splitting creates instability in relationships because one person can be viewed as either personified virtue or personified vice at different times, depending on whether they gratify the subject's needs or frustrates them."
To sum it up:
Seductive to one of you, rejecting of the other. It can shift according to the circumstances or his needs.
Playing one against the other.
Or he could provoke one of you so that he can make that person look like the bad guy, to take the heat off himself.
Actually, I would be surprised if this does not happen. It happens in my household all of the time.