There is something which makes me violently ill about the fact that Silena helped orchestrate the trap at the beginning of the last Olympian, which was 100% meant to kill Percy, and then, when Beckendorf died instead, it was Percy who tried to comfort her, who stood up for her at the councillors meeting, who defended her as a hero, even after finding out she was the spy and who thought about her like this throughout the last Olympian:
“Her mouth trembled. Ever since Beckendorf died she'd been getting worse, and every time I looked at her, it made me angry about his death all over again. Her expression reminded me of glass—like she might break any minute. I swore to myself that if I ever found the spy who'd cost her boyfriend his life, I would give him to Mrs. O'Leary as a chew toy. (The Last Olympian, Chapter 12)