Sweet heavens, YES! But they can't... at least not yet. Here's the root of the problem: Castle is shadowing Detective Beckett by choice. The writers have to keep them together without upsetting the balance too much, because Castle can always just leave if things get awkward (like he did in the Castle Season 2 finale). What makes this cyclical relationship different from that of, say, Ross and Rachel of Friends, is that those two knew all the same people, hung out at the same coffee shop, and were on a show called Friends. When things went south, it made sense they would still have to see each other. With Castle and Beckett, there's nothing connecting them plot-wise except Castle's insistence on following her around all the time to look at a dead body submerged in cat urine or dangling from a flag pole. Once they hook up, any major conflict seems like it would end with the same question: Why doesn't he just quit? It's not even quitting — he's not a cop. Plus, the anticipation of something happening is always more interesting. On the other hand, a hookup can only be avoided for so long before everyone gets aggravated. Maybe they should just sleep together and not tell any of us about it until they're sure it's serious. That would be very true to life.