Scottie-

You might want to browse some of the older posts, because this question comes up time and time again, but usually the long-term answer is make sure they're both neutered, loved, and given the same amount of attention, and they will eventually at least peacefully coexist. This of course, applies if one has been in your house longer than the other and they have both been neutered all along. If this is new behavior in old housemates, though, you might want to take the more agressive one to the vet. If this is new behavior in maturing kittens, neutering will likely take care of it.

Hope some of this helps.