Not what they seem:

[phoenix_kevin]

 Neville is quite a talent at 
> herbology so FakeMoody planted the book about waterplants on him, 
> during their little (off screen) tea time. FakeMoody expected 
Harry 
> to turn to everyone for help and he didn't. Finally, the night 
> before the task, FakeMoody had to plant Neville in the library 
with 
> Harry in hopes that the two would talk about the task. I like how 
> this was accomplished in the book much better with Dobby's 
> intervention but you can't have everything. So whilst (love saying 
> that, makes me feel so British) Neville is a whiz at herbology, he 
> was not what he seemed in this instance, but a plant! (Love that 
> little word-play). Also, Viktor's horrible evil look inside the 
maze 
> was the result of FakeMoody's doing as well. He put Viktor under 
the 
> Imperious curse to have him take out Cedric. So Viktor was the 
> unwilling victim and not an evil person, but I can't remember if 
> Harry picked up on that in the film. I think he did. Does anyone 
> else remember?
> Jen D.

It was a better storline allowing Neville to suggest the solution to 
Harry. It really advertised Neville's growing expertise in 
Herblology and allowed him to take a larger role in the movie. Over 
the entire movie series you could say Neville is becoming a great 
example of "Not what you'd expect".

I hadn't realised Viktor was under the Imperious curse. It certainly 
explains the almost demonic look he had. I don't remember Harry 
giving any indication he knew, perhaps he did.

I was in a discussion last night where it was mentioned that James 
had a lot more talent when he was Cedric's and as you said certainly 
more full of himself.