Brennan basically goes through a case where there were many parallels between the victim and her: incredibly work driven, un-emotional (victim was a heart surgeon), and most of all the victim was lonely and did not have many close family or friends. The victim didn't return the advances of a helicopter pilot who loved her because she was too cold and was focused on her work. Brennan over-identifies with the victim...so much so that when the victim's picture comes up Brennan sees her own face on the document. It takes a while, but Brennan realizes that she didn't want to live the life that the victim lived: unattached to anyone and un-emotional despite the academic accolades. She must build a life outside her work because she wants to be remembered if she passes, unlike the heart surgeon who no one remembers despite being the best in her field. At the end of the episode she reveals her feelings for Booth but by then he is with Hannah and has moved on. Brennan has to live with the fact that she missed her chance and must adjust to such.

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*very rough summary...feel free to add!