Interest piqued.

I absolutely hate Micah Bell. Therefore I could write him well. 
Sadie hates Micah more than I do. That wouldn't work.
Molly might be a good character. I find her to be a sad sack. If you wanted to play, Molly, I could do Dutch. He takes her for granted. They fight often.

Mary-beth strikes me as a grounded character, at least in the epilogue. But something dysfunctional must have drawn her into the Vanderlinde gang when she was younger.She might be a good character to explore.

Now, the best pairing would be Micah and Karen. They are both so flawed. They could be drunk and all over each other one minute to hung over, tired, miserable and arguing the next. Then one pleads forgiveness and the cycle starts over again. Kind of a cliche dysfunctional relationship.