I think that it had something to do with his first wife. Oh yes, mike knew his first wife, Orson disliked mike and ran him over. Mike had amnesia and got together with edie, mike remembered he loved susan, they got back together, edie got together with carlos, carlos wanted a baby, edie said she would do it for him, they had lots of sex, carlos found birth control in her bag on the day of gabby's wedding, he confronted her, told her he only wanted to be with her so he could knock her up, she ran off, went home and topped herself.
Orson was accused of killing his first wife, she turned up, tried to kill bree, then she fell out of a window (can't remember any more). Bree and Orson went on their honeymoon, danielle found out she was pregnant by edies nephew (the one that was trying to shag susans daughter), she went 'away'. Bree came back for Gabby's wedding sporting a big bump, she told Julie danielle decided to stay at a swiss boarding school for a year.
susan and mike got married, nothing interesting there.