"So, did Sara ever say anything to you about her and Grissom?"
"Not in so many words."
"So, you knew about the two of them?"
It's a lie. A complete and total lie, told right to Nick's face, but Greg can't bring himself to care.
He supposed that on some level, he had to have known. Someone had to be putting that smile on her face. She didn't try and chase after Grissom like she used to, either. Whenever he asked, she'd just give him that little half-grin, the one that said she thought what he said was funny but she didn't want to admit it.
It shouldn't be a lie. They've gotten closer since he had made the shift to CSI. At first it was just anecdotes to help Greg through his training, but soon enough, she was telling him about personal things as well. Greg wasn't lying when he told her was a good listener.
He told her things, too. He confided in her, especially during the whole Demetrius James debacle. He remembered the long conversations they had had over breakfasts. (In hindsight, he wondered why he didn't get suspicious when they went to breakfast nearly every day while Grissom was gone and suddenly it was back to twice a week after his return.) He talked to Sara about everything: his guilt, the nightmares, the lawsuit, Nick's over-protectiveness.
That was what got to him the most. She had known about his and Nick's relationship from the beginning. He had told about it when it was just a crush. She had smiled when he described their first date and the awkward first kiss that followed it great detail. He'd never tell Nick – because that would mean admitting Sara knew about them – but Greg knows that she probably helped him through a fight or two that could have been the end of the relationship.
Here they were, in the same boat, and he didn't even have inkling about it. Except for that one time with Mia, she had never given him reason not to trust her. He thought the feeling was mutual. Apparently not.
He thought they were friends. Now he's not so sure.
Summary: Greg didn't really know - but he should have.
Spoilers for "A La Cart", some season 7 and a vague "Swap Meet" reference. Greg/Sara friendship, mentions of Greg/Nick and GSR