Sometimes the best we get is a peaceful coexistence. But don't count out friendships just yet. What you are describing is pretty normal in cats being introduced to each other, as they have to do a certain amount of jockeying for position in the clowder. While cat clowders don't have an alpha in the same way that dog packs do (face it, cats don't take orders from ANYONE), there is always a pecking order that has to be determined. If one of them was really determined to hurt one of the others, they would almost certainly have done so.