The negotiations ended quickly. The Rat King couldn't refuse Noah's conditions after exposing its willingness to sever its ties with the Crystal City.
It turned out that the Crystal City had numerous castles situated past the edges of the human domain. Noah had already guessed that, but he didn't expect the Rats to be aware of that feature.
Still, they only knew the location of one of the castles, which was the new home of the fanatics who had survived the assault of the Legion.
The Rats weren't aware of the full power of the Crystal City. They only knew that the new location had multiple defenses capable of fending off any investigation.
'This should work in my favor,' Noah thought after assimilating that information. 'The Crystal City must have set powerful defenses for fear of a second assault. Losing the Snakes shouldn't be a problem once the battle starts.'