Nicely done, and a good twist on the archtypical idea of 'knowledge is power'! I always appreciate when a writer takes the concepts and worldbuilding of the games that inspired OPR and adapts them, rather than mimicking them outright, and you've done a good job of that here. I can see where your interpretation of the 'Rottekind' mimics that other rat faction, and where you've taken things in your own direction. (On the subject of Rottekind, I did wonder why the Ratmen - or Gritail, at least - is thinking of his people using a surface dweller term.)
When you write dialogue, it's better to use 'said', or simply not tag it at all, rather than any other term. 'Sneered', or even 'asked', can be left implied by what the character is saying, to whom, and why; 'said' is more or less invisible and helps dialogue flow more smoothly. Use body language rather than dialogue tags, if you need to: e.g. “This was taken from one of those surface folk. The ones you and Wivard had driven off. It was recovered from a body. I thought it important,” said Gritail, shaking from nose to tail-tip.
Like I said, I very much enjoyed the twist at the end; the last line is delicious and effectively conjures up visions of just what wickedness Verminax is going to get up to in the future. Thank you for the enjoyable read!