In the web serial https://www.royalroad.com/fiction/60396/thresholder, is the other thresholder a bug of the type that has been attacking the Natrix, or something similar to them, or naturally compatible in the way that Perry is compatible with the 'humans' of the worlds he's been to.

If there are multiple other thesholders, YES if any of them. If there are no other thesholders, or the story stops, N/A. If there isn't a clear answer, I'll resolve to a probability if I can do so confidently but might resolve N/A.

Resolution date extended as needed. I will not bet in this market.