What makes you guys think that Grissom has mistreated Nick over the course of the show?
I wouldn't say that I really think that, although I know others do and maybe they can share their reasons...things I might have missed. I think, tho, once you have it in your head that it's true, you'll see it everywhere, even if that may not be the intent.
For me it was probably "Evaluation Day" when he did that silly riddle with Nick to "prove" he wasn't ready for a solo DB.
Then he takes Warrick on a rollercoaster ride with him. This, after Warrick's gambling and negligence contributed to the death of a rookie CSI (not to mention he promoted him after being told to fire him).
That right there smacked of "teacher's pet" to me. It just seemed unfair...like at work when the boss keeps asking one person to go to lunch with them all the time and never any of the others.
So I think from then on I, and maybe others, thought back to that episode every time Grissom told Nick to "quit whining" ("Too Tough to Die") or whatever.
Then there was "Stalker" where he told Nick that it "wasn't about him". Let's see...there's a dead guy in his living room, his house is wrecked, he was spied on by a crazy man, thrown out a window, and held at gunpoint. I think it might have
something to do with him.
Then yeah, of course, "Daddy's Little Girl". Even tho, as you say, it was in Grissom's character to be that way, "It's over" just was kind of a slap in the face. I mean, the guy was traumatized beyond belief, and he gets an "It's over". But when Sara was picked up for a crime (DUI), Grissom went to her house and held her hand while she cried.
I get the fact that Sara and Warrick might have been missing the support of a strong family, but trying to fill that space for them doesn't seem like Grissom's character either. So for those of us who tend to obsess over every little thing we see on screen about Nick (as others do with their faves), it's easy to understand why we might think that way.
