“I thought this was a really sweet chance for Beckett to take control over something she’s committed herself to, she’s defined herself by. She faces a deep fear, she said - I don’t wanna be… I don’t wanna be defined by this anymore -. And that’s a huge decision, and that’s a big kind of growing step for the character, and also a step for her that brings her closer to a new relationship with Castle.” 

(Stana Katic talking about “Kill shot” last scene)