WP still insists (commentary on the finale) that Grissom never slept with LH. So, I'm going with that. She no doubt intrigued him, and obviously they had a close relationship, but that's the end of it. As for Catherine, again, just a friend. His personality is best suited for a GS relationship. I think tptb were mostly projecting a female fantasy. But Grissom is much more grounded in reality, as is Billy. In the end, I admire WP for his persistence. He was always more about staying true to the character.