Just when Kate Beckett thought she was getting the beautiful wedding she deserved, she was called to see Castle's car in flames on the side of the road in season 6 "For Better or Worse"
After 4 seasons, Kate showed up at Castle's door to tell him exactly what she wanted. The kiss up against the door in "Always" left shipper hearts aflutter for the entire summer.
Talk about a "Knockout" punch. In the Castle season 3 finale, Kate Beckett is shot by a sniper at Capt. Montgomery's funeral. All Castle can do is hold her and tell her he loves her.
In the Castle season 1 finale, "A Death in the Family" Kate Beckett is devastated when Castle does the one thing she asked him not to do, look into her mother's murder.
A charming man from Beckett's past turns up just before her wedding on the season finale of Castle. "For Better or Worse" is the 23rd episode of the show's sixth season.