Okay so here's the sort of storyline explanation to it lol.
It starts with the last couple eps of Season 2 and proceeds to the point where Castle finally makes a move and then Beckett has a little freak out about it but she comes around and admits her feelings for him, and then they start on the relationship path.
Corny I know, but whatever, I like it lol. And I called it "Walking the Line" because I think it's sort of about tip toeing back and forth over that line between friends and more.
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