Timeframe: Season 4, Episode 12.
Don't want to let you down, but I am hell bound; though this is for you, don't want to hide the truth.
Castle leaves the abandoned parking lot itching for a shower - the building wasn't dirty and neither was the man he met there, physically, anyway.
He did not fight for his place at Beckett's side so that he could get involved in lies and blackmail, especially when the lies are directed at Kate. He understands the need for them, sure, Beckett is a woman with a goal, and, if she knew -
He is doing this for her, it is obvious whatever happened back during her mother's murder is bigger than either of them realizes and he can't lose Kate, not again.
He will bear the weight of this sin, carry this lie with him, begging to crawl free from his throat every time she smiles a smile he's too damned to deserve.
A/N: Accepting prompts in the form of songs you'd like me to find lyrics from, or, if you have a specific lyric in mind, I'll try my best with that, too.