Revealing the false Moody?
In my story, which I'm still editing, Snape is the one to uncover the fake Moody in the end of book four. He wouldn't want to give himself away as past spy, and yet he wouldn't want to seem loyal to Dumbledore with Voldemort having returned. (Him finding out Moody will have happened after Voldemort returns). How can he go about uncovering Moody?
I'm in a bit of a pickle, and ideas are welcome!
Perhaps, he could learn from using a sneakescope. Or a powerful memory reversing potion such as the Vertasium (I think that is the name o.o.) Either way he has to tackle Moody on his own in private.
I'm sorry your post has lasted this long here with just one answer, Smellycat710. It's been the holidays, though. I hope you're still hanging in there.
Snape does not need motives (service to either Dumbledore or Voldemort) to uncover Moody. Snape can do it for his own edification or curiosity. The uncovered Crouch will not question or suspect anything but, in deviation from what happened in the book, you will have to make Crouch less perfect in his deviousness and slip just one time to give Snape the seed of suspicion toward him. In the book, even Dumbledore was fooled until the last minute of the Third Task. And it was Dumbledore who knew Moody well. For Snape to be given doubts, the false Moody will have to make a blatant uncharacteristic error. And you can go easily from here. Of course, you will have to make the error believable of an intelligent Death Eater as well.