What To Do When Your Two Cats Aren't Getting Along
So, your two cats aren't getting along? According to LifeHacker, there's a simple fix for that.
Scratch them each affectionately under the chin with the same hand, repeatedly.
This will mix their pheromones together. Eventually, they’ll think they’re from the same pack and share pheromones themselves.
They'll do that through that chin-rubbing behavior cats engage in.