Enemies could become the best companions. Companionship is based on a common interest, and the greater the interest the closer the companionship. What makes enemies of people, if not the eagerness, the passion for the same thing?
The space in a needle's eye is sufficient for two friends, but the whole world is scarcely big enough to hold two enemies. Solomon ibn Gabirol Whoso sheddeth man's blood, by man shall his blood be shed.