Castle pov...
I can't believe that Gates is allowing me to become a detective and become an official member of the team. It's even better that it will be a fast process.
At Beckett's apartment
We both arrive at the same time hardly believing the news that we would both be detectives in the same team fairly soon. "Rick what should we do for dinner" Kate asked me, I decided that tonight would be perfect to propose so I suggested we go out for dinner.
We had a very fancy dinner and she though it was just to celebrate today, on the way home we stopped off at the park and went to our swings.
We were just talking happily and I decided it was the perfect moment and got of the swing and down on one knee and asked "Katherine Houghton Beckett will you marry me?"
She had tears in her eyes and said "yes, always", I slipped the ring onto her finger and kissed her.
It was one of the happiest moments of my life as I knew it was the last time I would ever ask that question as we would be together for the rest of our lives.