Reality behind the fiction? Since when has "Castle" been that? Would the NYPD actually allow a mystery writer to evolve from shadowing one of their detectives to becoming her partner? I don't think so. "Castle" is a whole lot of other things but it isn't that and yeah the whole point of Slaughter's character was that he was supposed to be the opposite of Kate. I think he was written the way he should be.
The Alexis's arc has become interesting all of a sudden. I liked Rick's reaction to Slaughter implying that he was hitting on his daughter. Say what you will about Rick, but he IS a good father on the series.