We love looking back at past Castle and Beckett moments, and this one from Season 3, Episode 21: "The Dead Pool" happens to be one of our favorites.
When another mystery writer, Alex Conrad, starts hanging around the precinct, Rick gets a case of the green-eyed monster. "I'm jealous. There I said it," he confesses. Beckett's face melts into a sweet smile. "From now on, I'm a one writer girl," she says.
Sigh. This scene still gives us butterflies!