My wife and I were talking about the rivalry between multi and ning, and how it might be fun to encourage the animosity between the two group, at least for the sake of a story line. (Only for the sake of a story line. As I would never encourage such things between groups in real life.) The premise is simple the two groups for whatever reason just don’t like each other. The exact reason can be for the players involved to decide. However, I do have a couple ideas.
The first being, after the heroes (multi) save Hellifyno from another invasion. (They just pushed the Tremere from the city if I got my facts straight) The citizens (ning) seem indifferent to it all. They seem not to care about the sacrifices that the heroes made in defense of Hellifyno.
The second idea is much like the first but instead of being indifferent the people of (ning) blames the heroes for all the troubles Helliyfno has endured and decides to rebel against them.
Assuming that anyone likes this idea, the two groups due to the tension sends spies into the other to gather information and other such things, because spying is fun. We could have the people in comments get involved by encouraging them to support one side or another, or even start their own group of we think you are both crazy, and we are going over here.