Ooh -- good discussion!! There are characters that may hold allegiance to the Death Eaters, who weren't thought to be. This may be going off topic a little, but there is also the possibility of the imperius curse being used on Good Members to make them go against their own side and do the Dark Lord's bidding. We saw this in the last book with Thicknesse being under the Imperius, and I believe there was also a couple more Ministry workers under the Imperius. Could Rita have been under the Imperius, or maybe she was just completely on Fudge's side so that anything she did was for him? Could it have been out of lust? Personally, I feel that Rita was too on Fudge's side where anything she did was for him. If there was anything that he disproved of (admitting to the return of the Dark Lord - since it was feared), then she would be working for him to cover up all proof.
In reality then, there were three sides in this story: the Death Eater side, Harry's side (or light side), and the side that is neither good or bad but just lives in fear.
I have more, but just forgot my train of thought... so I will speculate later
