Enemies do arise in life. I imagine that people gain and deal with enemies in multiple ways. In my life, enemies have arisen in ways that surprised me. I have never been one to expect another person to be an enemy, so when enemies arise, I am always surprised.
What is an enemy?
An enemy works against your good living and good will. It's possible that you can unknowingly be an enemy of another, you can actually work against someone's good living without knowing that. With sensitive communication, we can help one another to be allies and friends rather than enemies, but that's not always the case, so it's possible to be an enemy of someone without even knowing it.
And, of course, there are those who knowingly act against your good will too. It is difficult for me to imagine this, but I know that it happens.
What do you do about your enemies?
I think you have to calculate the risk. Is the enemy someone who is a nuisance--someone who will not cause long term harm, or is the enemy someone who is a danger to you.
In some cases, you may be able to confront your enemy to find out why they've done what they did, and then see how they react. That gives people a chance to make amends or change.
There are other cases, where it's not worth your time or effort to confront the enemy, and it's just better to stay away from the situation.
Further there are those that keep you on your toes--those that are a threat to you, people you have to actively find ways to be safe from.
Fortunately I have few enemies in life, and those that I have are more the result of circumstance than any will to hurt or harm another--life paths have created this struggle.
It's good to acknowledge your enemies, think about the roots of that situation, and in any way possible work against harm and in favor of positivity and safety. Onward.